diff --git a/01-hello.rb b/01-hello.rb
index e0e7bbf..11399c5 100644
--- a/01-hello.rb
+++ b/01-hello.rb
@@ -4,5 +4,5 @@
 your_name = gets
 
 # ...
-
-puts "(请替换成最后的答案)"
\ No newline at end of file
+print your_name + "is "
+puts "smartful"
diff --git a/02-variable.rb b/02-variable.rb
index a5a4753..9555713 100644
--- a/02-variable.rb
+++ b/02-variable.rb
@@ -1,7 +1,7 @@
 # 题目: 交换 a, b 变数的值
 
-a = 1
-b = 2
+a = 7
+b = 8
 
 puts "a 是 #{a}"
 puts "b 是 #{b}"
@@ -10,4 +10,3 @@
 
 puts "a 应该是 2，现在是 #{a}"
 puts "b 应该是 1，现在是 #{b}"
-
diff --git a/03-triangle.rb b/03-triangle.rb
index fafec03..f5ba257 100644
--- a/03-triangle.rb
+++ b/03-triangle.rb
@@ -1,5 +1,7 @@
 # 题目: 使用者输入直角三角形的宽和高，输出三角形的面积
 
+
+
 print "请输入直角三角形的高，然后按 Enter: "
 a = gets
 
@@ -8,4 +10,6 @@
 
 # .....
 
-puts "直角三角形的面积是: _________"
\ No newline at end of file
+puts "直角三角形的面积是: #{ a.to_f * b.to_f / 2 }"
+
+#second time
diff --git a/04-pizzas.rb b/04-pizzas.rb
index 4c2521f..6aa3b45 100644
--- a/04-pizzas.rb
+++ b/04-pizzas.rb
@@ -8,5 +8,5 @@
 
 # .....
 
-puts "每人可分得几片: _________ 片"
-puts "还剩下几片: _________ 片"
\ No newline at end of file
+puts "每人可分得几片:#{ (pizzas.to_i / people.to_i).floor } 片"
+puts "还剩下几片: #{ pizzas.to_i % people.to_i  } "
diff --git a/05-bmi.rb b/05-bmi.rb
index 67efdff..eec7755 100644
--- a/05-bmi.rb
+++ b/05-bmi.rb
@@ -4,14 +4,23 @@
 # 如果 BMI >= 24，显示过重
 # 如果 BMI 介于 18.5 ~ 24，显示正常
 
+
 print "请输入您的体重(公斤)，然后按 Enter: "
 weight = gets
 
 print "请输入您的身高(厘米)，然后按 Enter: "
 height = gets
 
-# .....
+BMI = (weight.to_f / (height.to_f/100) ** 2).round(2)
+
+puts "您的 BMI 是: #{ BMI }"
 
-puts "您的 BMI 是: _________"
+if BMI < 18.5
+  puts "您的 BMI 结果是: 过轻"
+elsif BMI > 24
+  puts "您的 BMI 结果是: 过重"
+else
+  puts "您的 BMI 结果是: 正常"
+end
 
-puts "您的 BMI 结果是: _________(过轻或正常或过重)"
\ No newline at end of file
+#bug :输入任意非数字串
diff --git a/06-integer-positive.rb b/06-integer-positive.rb
new file mode 100644
index 0000000..be3cd77
--- /dev/null
+++ b/06-integer-positive.rb
@@ -0,0 +1,23 @@
+# 题目: 输入一个数字 x，请判断是否正数、零或负数，以及是不是偶数
+
+
+print "请输入一个整数，然后按 Enter: "
+x = gets
+
+# ....
+
+if x.to_f > 0
+  puts "正数"
+elsif x.to_f < 0
+  puts "负数"
+else
+  puts "0"
+end
+
+if x.to_f % 2 == 0
+  puts "偶数"
+else
+  puts "奇数"
+end
+
+#bug :输入任意非数字串为0和偶数
diff --git a/06-interger-positive.rb b/06-interger-positive.rb
deleted file mode 100644
index a240f5f..0000000
--- a/06-interger-positive.rb
+++ /dev/null
@@ -1,10 +0,0 @@
-# 题目: 输入一个数字 x，请判断是否正数、零或负数，以及是不是偶数
-
-
-print "请输入一个整数，然后按 Enter: "
-x = gets
-
-# ....
-
-puts "这个数是_____ (正数或零或负数)"
-puts "这个数是_____ (偶数或奇数)"
\ No newline at end of file
diff --git a/07-abcde.rb b/07-abcde.rb
index 5d0c8c3..19e8b4d 100644
--- a/07-abcde.rb
+++ b/07-abcde.rb
@@ -17,6 +17,28 @@
 print "请输入一个整数z，然后按 Enter: "
 z = gets
 
-# ....
+q = x.to_f
+w = y.to_f
+e = z.to_f
 
-puts "结果是________(A或B或C或D或E)"
\ No newline at end of file
+if q < 0
+  puts "A"
+elsif q > 0 && w > 0
+  if e > 0
+    puts "B"
+  elsif e < 0
+    puts "C"
+  else
+    puts "none1"
+  end
+elsif q > 0 && w < 0
+  if e > 0
+    puts "D"
+  elsif e < 0
+    puts "E"
+  else
+    puts "none2"
+  end
+else
+  puts "none3"
+end
diff --git a/08-find-max.rb b/08-find-max.rb
index 9e6e643..3b52244 100644
--- a/08-find-max.rb
+++ b/08-find-max.rb
@@ -9,6 +9,18 @@
 print "请输入一个数字z，然后按 Enter: "
 z = gets
 
-# ....
+q = x.to_f
+w = y.to_f
+e = z.to_f
+
+if q >= w && q >= e
+  puts "最大的数是 #{x}"
+elsif w >= q &&  w >= e
+  puts "最大的数是 #{y}"
+elsif e >= w &&  e >= q
+  puts "最大的数是 #{z}"
+else
+  puts "none"
+end
 
-puts "最大的数是 ________(x或y或z)"
\ No newline at end of file
+# ....
diff --git a/09-function.rb b/09-function.rb
index b1f922d..acc468e 100644
--- a/09-function.rb
+++ b/09-function.rb
@@ -1,7 +1,7 @@
 # 题目: 输入直角三角形的宽和高，输出三角形的面积
 
 def calculate_area(a, b)
-  # ....
+  a.to_f * b.to_f / 2
 end
 
 print "请输入直角三角形的高，然后按 Enter: "
@@ -12,4 +12,4 @@ def calculate_area(a, b)
 
 answer = calculate_area(a,b)
 
-puts "直角三角形的面积是: #{answer}"
\ No newline at end of file
+puts "直角三角形的面积是: #{answer}"
diff --git a/10-function.rb b/10-function.rb
index bb450fb..1701b16 100644
--- a/10-function.rb
+++ b/10-function.rb
@@ -1,6 +1,20 @@
 # 题目: 使用者输入 x,y,z，请输出三个数中最大的数
 
 def find_max(x, y, z)
+  q = x.to_f
+  w = y.to_f
+  e = z.to_f
+
+  if q >= w && q >= e
+    return x
+  elsif w >= q &&  w >= e
+    return y
+  elsif e >= w &&  e >= q
+    return z
+  else
+    return "none"
+  end
+
 end
 
 print "请输入一个数字x，然后按 Enter: "
@@ -16,4 +30,4 @@ def find_max(x, y, z)
 
 answer = find_max(x,y,z)
 
-puts "最大的数是 #{answer}"
\ No newline at end of file
+puts "最大的数是 #{answer}"
diff --git a/11-seven.rb b/11-seven.rb
index 26c221d..67c1cc9 100644
--- a/11-seven.rb
+++ b/11-seven.rb
@@ -2,8 +2,9 @@
 
 i = 1
 while ( i <= 100 )
-
-  # ....
+  if (7*i) < 100
+    puts 7*i
+  end
 
   i+=1
-end
\ No newline at end of file
+end
diff --git a/12-sum-even.rb b/12-sum-even.rb
index 73879bb..dc29380 100644
--- a/12-sum-even.rb
+++ b/12-sum-even.rb
@@ -1,13 +1,11 @@
 # 题目: 求 1~100 所有偶数的和
 
-i = 1
+i = 0
 total = 0
 
 while ( i <= 100 )
-
-  # ....
-
-  i+=1
+  total += i
+  i+=2
 end
 
-puts total
\ No newline at end of file
+puts total
diff --git a/13-nn.rb b/13-nn.rb
index ac0a43b..bff10d2 100644
--- a/13-nn.rb
+++ b/13-nn.rb
@@ -2,10 +2,19 @@
 
 print "请输入数字 N，然后按 Enter: "
 n = gets
+n = n.to_i
 
-# while ( ... )
-#   while ( ...)
-#
-#   end
-# end
+i = 0
 
+while ( i <= n )
+  j = 0
+
+  while ( j <= n)
+
+    puts "#{i} * #{j} = #{i*j}"
+    j += 1
+
+  end
+
+  i += 1
+end
diff --git a/14-prime.rb b/14-prime.rb
index 8cf1692..7a3a77c 100644
--- a/14-prime.rb
+++ b/14-prime.rb
@@ -1,11 +1,26 @@
 # 输入一个数字 N，请检查是不是质数
 
 def is_prime(n)
-# ....
+  if n < 2
+    return false
+  elsif n == 2 || n == 3
+    return true
+  else
+    i = 2
+    while ( i <= (n/2) )
+      if (n % i) != 0
+        return true
+      else
+        return false
+      end
+    i += 1
+    end
+  end
 end
 
 print "请输入数字 N，然后按 Enter: "
 n = gets
+n = n.to_f
 
 if is_prime(n.to_i)
   puts "这是质数"
diff --git a/15-guess-number.rb b/15-guess-number.rb
index 48f9dca..f577082 100644
--- a/15-guess-number.rb
+++ b/15-guess-number.rb
@@ -6,12 +6,13 @@
   print "请猜一个 0~99 的数字 N，然后按 Enter: "
   n = gets
 
-  #puts "太低了，再猜一次"
-  #puts "太高了，再猜一次"
-
   if n.to_i == target
     puts "恭喜猜中啦! "
     break
+  elsif n.to_i < target
+    puts "太低了，再猜一次"
+  else
+    puts "太高了，再猜一次"
   end
 
-end
\ No newline at end of file
+end
diff --git a/16-array-sum.rb b/16-array-sum.rb
index 9b4910b..5312ced 100644
--- a/16-array-sum.rb
+++ b/16-array-sum.rb
@@ -1,11 +1,17 @@
 # 给定一阵列内含数字，输出最大值
 
 def find_max(array)
-  #....
+  max = array[0]
+  for i in 1..((array.length)-1)
+    if array[i] > max
+      max = array[i]
+    end
+  end
+
+  return max
 end
 
-arr = [8, 12, 36, 53, 9, 75, 3, 71, 59, 88]
+arr = [888, 12, 36, 53, 9, 75, 3, 71, 59, 88]
 
 max = find_max(arr)
-puts "Max is #{max}" # 应该是 88
-
+puts "Max is #{max}" # 应该是 888
diff --git a/17-array-stats.rb b/17-array-stats.rb
index 0af81bb..40e3723 100644
--- a/17-array-stats.rb
+++ b/17-array-stats.rb
@@ -12,9 +12,18 @@
   end
 end
 
+total = 0
+for i in arr
+  total += i
+end
+
+average = total.to_f / arr.length
+max = arr.max
+min = arr.min
+
 puts arr.to_s
 
-puts "总和是 _____"
-puts "平均是 _____"
-puts "最大值是 _____"
-puts "最小值是 _____"
\ No newline at end of file
+puts "总和是 #{total}"
+puts "平均是 #{average}"
+puts "最大值是 #{max}"
+puts "最小值是 #{min}"
diff --git a/18-square.rb b/18-square.rb
index 226e1c1..8bfe5d6 100644
--- a/18-square.rb
+++ b/18-square.rb
@@ -4,7 +4,10 @@
 
 print "请输入数字 N，然后按 Enter: "
 n = gets
+n = n.to_i
 
-# ...
+for i in 0..n-1
+  arr << i**2
+end
 
-puts arr.to_s
\ No newline at end of file
+puts arr.to_s
diff --git a/19-filter.rb b/19-filter.rb
index ef7e515..7bbcbde 100644
--- a/19-filter.rb
+++ b/19-filter.rb
@@ -1,9 +1,20 @@
 # 给定一阵列内含数字，输出另一个数组只包含偶数
 
+
+
+
 def filter_even(arr)
-  #...
+  result = []
+
+  arr.each do |i|
+    if i % 2 == 0
+      result << i
+    end
+  end
+
+  return result
 end
 
-arr =  [7, 68, 42, 46, 9, 91, 77, 46, 86, 1]
+arr =  [7, 68, 42, 46, 9, 91, 77, 46, 86, 1, 0]
 
-puts filter_even(arr).to_s # 应该是 [68, 42, 46, 46, 86]
\ No newline at end of file
+puts filter_even(arr).to_s # 应该是 [68, 42, 46, 46, 86]
diff --git a/20-sorting.rb b/20-sorting.rb
index 5f82c08..82dbeb0 100644
--- a/20-sorting.rb
+++ b/20-sorting.rb
@@ -2,10 +2,13 @@
 # Hint: 可用 arr.sort 排序，和 arr.uniq 去除重复
 
 def filter_even(arr)
-  #...
+  arr.sort!
+  arr.uniq!
+  arr
 end
 
 arr =  [7, 68, 42, 46, 9, 91, 77, 46, 86, 1]
 
+a = filter_even(arr).to_s
 
-puts "________" # 应该是 [42, 46, 68, 86]
\ No newline at end of file
+puts "#{a}" # 应该是 [42, 46, 68, 86]
diff --git a/21-selection-sort.rb b/21-selection-sort.rb
index e5e7eae..890ec4c 100644
--- a/21-selection-sort.rb
+++ b/21-selection-sort.rb
@@ -2,11 +2,25 @@
 # https://zh.wikipedia.org/wiki/选择排序
 
 def selection_sort(arr)
-  #...
+
+  for i in (0..arr.size-1)
+    for j in (i+1)..(arr.size-1)
+      if arr[j] < arr[i]
+        tmp = arr[i]
+        arr[i] = arr[j]
+        arr[j] = tmp
+      end
+    end
+  end
+  
+  return arr
+
 end
 
 arr =  [7, 68, 42, 46, 9, 91, 77, 46, 86, 1]
 
 answer = selection_sort(arr)
 
-puts answer.to_s # 应该是 [1, 7, 9, 42, 46, 46, 68, 77, 86, 91]
\ No newline at end of file
+puts answer.inspect
+# 应该是 [1, 7, 9, 42, 46, 46, 68, 77, 86, 91]
+# inspect also aliased as: to_s
diff --git a/22-missing.rb b/22-missing.rb
index 6898714..af70410 100644
--- a/22-missing.rb
+++ b/22-missing.rb
@@ -1,9 +1,24 @@
 # 给定一阵列内含数字，请输出 0~9 中不见的数字
 
 def find_missing(arr)
-  # ...
+  result = []
+  flag = [0,0,0,0,0,0,0,0,0,0]
+
+  for a in arr
+    flag[a] = 1 #index 位置为1
+  end
+
+  for i in 0..(flag.size-1)
+    if ( flag[i] == 0 )
+      result << i
+    end
+  end
+
+  result
 end
 
-answer = find_missing( [2,2,1,5,8,4] )
+arr = [2,2,1,5,8,4]
+
+answer = find_missing( arr ).inspect
 
-puts answer.to_s # 应该是 [0,3,6,7,9]
+puts answer # 应该是 [0,3,6,7,9]
diff --git a/23-hash-max.rb b/23-hash-max.rb
index 6fb227e..443117d 100644
--- a/23-hash-max.rb
+++ b/23-hash-max.rb
@@ -1,7 +1,8 @@
-# 给定一 Hash，输出有最大 value 的 key
+#给定一 Hash，输出有最大 value 的 key
 
 def find_max(hash)
-  # ...
+  result = hash.values.max
+  hash::key(result)
 end
 
 h = {
@@ -11,9 +12,7 @@ def find_max(hash)
   "d" => 80,
   "e" => 10
 }
-
+#
 answer = find_max(h)
 
 puts "有最大 value 的是 #{answer}" # 应该是 d
-
-
diff --git a/24-hash-even.rb b/24-hash-even.rb
index 9da9605..c2c880b 100644
--- a/24-hash-even.rb
+++ b/24-hash-even.rb
@@ -2,7 +2,17 @@
 
 def find_even_keys(hash)
 
-  # ... (请回传一个数组)
+  result1 = []
+  h = hash.values
+  for i in h
+    result1 << i if i % 2 == 0
+  end
+
+  result2 = []
+  for j in result1
+    result2 << hash::key(j)
+  end
+  result2
 
 end
 
@@ -17,5 +27,3 @@ def find_even_keys(hash)
 answer = find_even_keys(h)
 
 puts "有偶数 value 的 keys 有 #{answer}" # 应该是数组 [b,d,e]
-
-
diff --git a/25-hash-count.rb b/25-hash-count.rb
index 2167335..777c767 100644
--- a/25-hash-count.rb
+++ b/25-hash-count.rb
@@ -3,8 +3,9 @@
 def count(arr)
   h = {}
 
-  arr.each do |i|
-    # ...
+  arr.uniq.each do |i|
+    a = arr.count(i)
+    h[i] = a
   end
 
   return h # 回传一个 hash
@@ -15,4 +16,3 @@ def count(arr)
 answer = count(arr)
 
 puts answer # 答案应该是 {"a"=>3, "d"=>6, "c"=>5, "b"=>1, "e"=>5}
-
diff --git a/26-hash-filter.rb b/26-hash-filter.rb
index 51ade64..4c86a8e 100644
--- a/26-hash-filter.rb
+++ b/26-hash-filter.rb
@@ -7,10 +7,30 @@
   { "name" => "Steven", "age" => 22 },
   { "name" => "Vincent", "age" => 6 },
 ]
+def filter_and_sort(arr)
 
-# ....
+  h = []
+  arr.each do |a|
+    if a["age"] > 18
+      h << a
+    end
+    h
+  end
 
-puts "所有成年人，并由小到大: _________"
+  (0..h.length-1).each do |i|
+    minname, index = h[i], i
+    (i+1..h.length-1).each do |j|
+      minname, index = h[j], j if h[j]["age"] < minname["age"]
+      h[i], h[index] = h[index], h[i]  #这句和 21-selection-sort 一样 ，但此句未理解
+    end
+  end
+  return h
+
+end
+
+h = filter_and_sort(arr)
+
+puts "所有成年人，并由小到大: #{h}"
 
 # 答案应该是
 #[
@@ -18,3 +38,21 @@
 #  { "name" => "Peter", "age" => 30 },
 #  { "name" => "David", "age" => 45 }
 #]
+
+# 另一种思路
+# ages = []
+# arr.each do |h|
+#   ages.push(h["age"])
+# end
+# ages = ages.sort
+# newArr = []
+# for age in ages
+#   arr.each do |h|
+#     if age == h["age"]
+#       newArr.push(h)
+#       break
+#     end
+#   end
+# end
+#
+# puts "所有成年人，并由小到大: #{newArr}"
diff --git a/27-class.rb b/27-class.rb
index 8cec2c9..138c333 100644
--- a/27-class.rb
+++ b/27-class.rb
@@ -1,5 +1,10 @@
 class Person
-  # ...
+  attr_accessor :first_name
+  attr_accessor :last_name
+
+  def greet
+    puts "Hi, #{first_name}, #{last_name} "
+  end
 end
 
 p1 = Person.new
@@ -11,6 +16,3 @@ class Person
 p2.first_name = "William"
 p2.last_name = "Zhang"
 p2.greet # 输出 "Hello, William Zhang"
-
-
-
diff --git a/28-word-count.rb b/28-word-count.rb
index 2643123..cdcc464 100644
--- a/28-word-count.rb
+++ b/28-word-count.rb
@@ -2,4 +2,13 @@
 
 doc = File.read("wordcount.txt")
 
-# ...
+words = doc.split   # words = doc.split(" ")
+
+words_count = {}
+
+for w in words
+  words_count[w] ||= 0
+  words_count[w] += 1
+end
+
+puts(words_count)
diff --git a/29-todos.rb b/29-todos.rb
index 0bddde2..5c907f8 100644
--- a/29-todos.rb
+++ b/29-todos.rb
@@ -1,5 +1,4 @@
 # 简易 Todo 代办事项应用
-
 text = File.read("todos.txt")
 
 todos = []
@@ -17,17 +16,35 @@
 
   if command == "add"
     print "请输入代办事项: "
-    # ...
+
+    task = gets.chomp
+    todos << task
+    todos.each_with_index do |todo, index|
+      puts "#{index}: #{todo}"
+    end
+
+
   elsif command == "remove"
     print "请输入要删除的编号: "
-    # ...
+
+    task = gets.chomp
+    todos.delete_at(task.to_i)
+    todos.each_with_index do |todo, index|
+      puts "#{index}: #{todo}"
+    end
+
   elsif command == "save"
     puts "存盘离开"
 
-    # ...
+    File.open("todos.txt", "w+") do |f|
+      todos.each do |todo|
+        f << todo
+        f << "\n"
+      end
+    end
+
     break;
   else
     puts "看不懂，请再输入一次"
   end
 end
-
diff --git a/README.txt b/README.txt
new file mode 100644
index 0000000..0f0b1c8
--- /dev/null
+++ b/README.txt
@@ -0,0 +1 @@
+for changing name