diff --git a/01-hello.rb b/01-hello.rb
index e0e7bbf..a978e84 100644
--- a/01-hello.rb
+++ b/01-hello.rb
@@ -5,4 +5,4 @@
 
 # ...
 
-puts "(请替换成最后的答案)"
\ No newline at end of file
+puts "Hello, #{your_name}"
diff --git a/02-variable.rb b/02-variable.rb
index a5a4753..53b4c95 100644
--- a/02-variable.rb
+++ b/02-variable.rb
@@ -6,8 +6,9 @@
 puts "a 是 #{a}"
 puts "b 是 #{b}"
 
-# ...
+c = a
+a = b
+b = c
 
 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..77dfaa3 100644
--- a/03-triangle.rb
+++ b/03-triangle.rb
@@ -6,6 +6,8 @@
 print "请输入直角三角形的底边，然后按 Enter: "
 b = gets
 
+
 # .....
+s = (a.to_f*a.to_f)/2
 
-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: #{s}"
diff --git a/04-pizzas.rb b/04-pizzas.rb
index 4c2521f..cf93c0e 100644
--- a/04-pizzas.rb
+++ b/04-pizzas.rb
@@ -7,6 +7,11 @@
 people = gets
 
 # .....
+ s1 = pizzas
+ s2 = people
+ t1 = s1.to_i/s2.to_i
+ t2 = s1.to_i%s2.to_i
 
-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: #{t1} 片"
+puts "还剩下几片: #{t2} 片"
diff --git a/05-bmi.rb b/05-bmi.rb
index 67efdff..9bf7c09 100644
--- a/05-bmi.rb
+++ b/05-bmi.rb
@@ -11,7 +11,18 @@
 height = gets
 
 # .....
+w = weight
+h = height
+b = w.to_f/(h.to_f*h.to_f)*100*100
 
-puts "您的 BMI 是: _________"
+if b < 18.5
+  t = "过轻"
+elsif b >= 24
+  t = "过重"
+else ( b >= 18.5 ) && ( b < 24 ) 
+  t = "正常"
+end
 
-puts "您的 BMI 结果是: _________(过轻或正常或过重)"
\ No newline at end of file
+puts "您的 BMI 是: #{b}"
+
+puts "您的 BMI 结果是: #{t}(过轻或正常或过重)"
diff --git a/06-interger-positive.rb b/06-interger-positive.rb
index a240f5f..11f2694 100644
--- a/06-interger-positive.rb
+++ b/06-interger-positive.rb
@@ -5,6 +5,23 @@
 x = gets
 
 # ....
+s = x.to_i
+s1 = s%2
 
-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
+if s < 0
+  t = "负数"
+elsif s > 0
+  t = "正数"
+else
+  t = "零"
+end
+
+if s1 > 0
+  t1 = "奇数"
+elsif s1 == 0
+  t1 = "偶数"
+end
+
+
+puts "这个数是: #{t}(正数或零或负数)"
+puts "这个数是: #{t1} (偶数或奇数)"
diff --git a/07-abcde.rb b/07-abcde.rb
index 5d0c8c3..e890710 100644
--- a/07-abcde.rb
+++ b/07-abcde.rb
@@ -18,5 +18,43 @@
 z = gets
 
 # ....
+=begin
+t1 = x.to_i
+t2 = y.to_i
+t3 = z.to_i
 
-puts "结果是________(A或B或C或D或E)"
\ No newline at end of file
+if t1 < 0
+  s = "A"
+elsif t1 > 0 && t2 > 0 && t3 > 0
+  s = "B"
+elsif t1 > 0 && t2 > 0 && t3 < 0
+  s = "C"
+elsif t1 > 0 && t2 < 0 && t3 > 0
+  s = "D"
+else t1 >0 && t2 < 0 && t3 < 0
+  s = "E"
+end
+=end
+
+x = x.to_i
+y = y.to_i
+z = z.to_i
+
+if x < 0
+  s = "A"
+elsif x > 0 && y > 0
+  if z > 0
+    s = "B"
+  elsif z < 0
+    s = "C"
+  end
+elsif x > 0 && y < 0
+  if z > 0
+    s = "D"
+  elsif z < 0
+    s = "E"
+  end
+end
+
+
+puts "结果是: #{s} (A或B或C或D或E)"
diff --git a/08-find-max.rb b/08-find-max.rb
index 9e6e643..f0ba7a1 100644
--- a/08-find-max.rb
+++ b/08-find-max.rb
@@ -10,5 +10,20 @@
 z = gets
 
 # ....
+x = x.to_i
+y = y.to_i
+z = z.to_i
 
-puts "最大的数是 ________(x或y或z)"
\ No newline at end of file
+
+
+if x >= y && x >= z
+  t = "x"
+elsif y >= z && y >= x
+  t = "y"
+elsif z >= x && z >= y
+  t = "z"
+end
+
+# t = [x, y, z].max
+
+puts "最大的数是: #{t} (x或y或z)"
diff --git a/09-function.rb b/09-function.rb
index b1f922d..6fa1049 100644
--- a/09-function.rb
+++ b/09-function.rb
@@ -2,6 +2,9 @@
 
 def calculate_area(a, b)
   # ....
+  a = a.to_f
+  b = b.to_f
+  s = ( a * b ) / 2
 end
 
 print "请输入直角三角形的高，然后按 Enter: "
@@ -12,4 +15,4 @@ 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..35a511b 100644
--- a/10-function.rb
+++ b/10-function.rb
@@ -1,6 +1,18 @@
 # 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)
+  x = x.to_f
+  y = y.to_f
+  z = z.to_f
+
+  if x >= y && x >= z
+    t = "x"
+  elsif y >= z && y >= x
+    t = "y"
+  elsif z >= x && z >= y
+    t = "z"
+  end
+
 end
 
 print "请输入一个数字x，然后按 Enter: "
@@ -16,4 +28,4 @@ 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..82def6d 100644
--- a/11-seven.rb
+++ b/11-seven.rb
@@ -4,6 +4,9 @@
 while ( i <= 100 )
 
   # ....
-
-  i+=1
-end
\ No newline at end of file
+  if i % 7 == 0
+    puts i
+  end
+    i += 1
+  
+end
diff --git a/12-sum-even.rb b/12-sum-even.rb
index 73879bb..34e8aec 100644
--- a/12-sum-even.rb
+++ b/12-sum-even.rb
@@ -7,7 +7,12 @@
 
   # ....
 
+  if i % 2 == 0
+    puts i
+    total += i
+  end
+
   i+=1
 end
 
-puts total
\ No newline at end of file
+puts total
diff --git a/13-nn.rb b/13-nn.rb
index ac0a43b..1d44ae8 100644
--- a/13-nn.rb
+++ b/13-nn.rb
@@ -2,10 +2,21 @@
 
 print "请输入数字 N，然后按 Enter: "
 n = gets
+n = n.to_i
+x = x.to_i
+y = y.to_i
 
 # while ( ... )
 #   while ( ...)
 #
 #   end
 # end
-
+x = 0
+while x <= n
+  y = 0
+  while y <= n
+    puts "#{x} x #{y} = #{x*y}"
+    y += 1
+  end
+  x += 1
+end
diff --git a/14-prime.rb b/14-prime.rb
index 8cf1692..7af5487 100644
--- a/14-prime.rb
+++ b/14-prime.rb
@@ -2,6 +2,24 @@
 
 def is_prime(n)
 # ....
+  if n < 2
+    return false
+  end
+
+  if n == 2
+    return true
+  end
+
+  if n > 2
+    i = 2
+    while i <= n/2
+      if n % i == 0
+        return false
+      end
+      i += 1
+    end
+    return true
+  end
 end
 
 print "请输入数字 N，然后按 Enter: "
diff --git a/15-guess-number.rb b/15-guess-number.rb
index 48f9dca..88a1a46 100644
--- a/15-guess-number.rb
+++ b/15-guess-number.rb
@@ -12,6 +12,10 @@
   if n.to_i == target
     puts "恭喜猜中啦! "
     break
+  elsif n.to_i > target
+    puts "太高了，再猜一次"
+  elsif n.to_i < target
+    puts "太低了，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..c702f39 100644
--- a/16-array-sum.rb
+++ b/16-array-sum.rb
@@ -2,10 +2,16 @@
 
 def find_max(array)
   #....
+  m = array[0]
+  array.each do |i|
+    if m < i
+      m = i
+    end
+  end
+  return m
 end
 
 arr = [8, 12, 36, 53, 9, 75, 3, 71, 59, 88]
 
 max = find_max(arr)
 puts "Max is #{max}" # 应该是 88
-
diff --git a/17-array-stats.rb b/17-array-stats.rb
index 0af81bb..e03a37c 100644
--- a/17-array-stats.rb
+++ b/17-array-stats.rb
@@ -14,7 +14,22 @@
 
 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
+sum = 0
+m = n = arr[0]
+arr.each do |i|
+  sum += i
+  if m < i
+    m = i
+  end
+  if n > i
+    n = i
+  end
+end
+
+average = sum / arr.size
+
+
+puts "总和是 #{sum}"
+puts "平均是 #{average}"
+puts "最大值是 #{m}"
+puts "最小值是 #{n}"
diff --git a/18-square.rb b/18-square.rb
index 226e1c1..8637155 100644
--- a/18-square.rb
+++ b/18-square.rb
@@ -5,6 +5,12 @@
 print "请输入数字 N，然后按 Enter: "
 n = gets
 
+n = n.to_i
+
+(0..n-1).each_with_index do |i|
+  # arr.push (i*i)
+  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..1b16f9b 100644
--- a/19-filter.rb
+++ b/19-filter.rb
@@ -2,8 +2,15 @@
 
 def filter_even(arr)
   #...
+  arr2 = []
+  arr.each do |i|
+    if i % 2 == 0
+      arr2.push (i)
+    end
+  end
+  arr2
 end
 
 arr =  [7, 68, 42, 46, 9, 91, 77, 46, 86, 1]
 
-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..876372a 100644
--- a/20-sorting.rb
+++ b/20-sorting.rb
@@ -3,9 +3,17 @@
 
 def filter_even(arr)
   #...
+  arr2 = []
+  arr.each do |i|
+    if i % 2 == 0
+      arr2.push(i)
+    end
+  end
+  arr2 = arr2.uniq
+  arr2 = arr2.sort
 end
 
 arr =  [7, 68, 42, 46, 9, 91, 77, 46, 86, 1]
 
 
-puts "________" # 应该是 [42, 46, 68, 86]
\ No newline at end of file
+puts filter_even(arr).to_s # 应该是 [42, 46, 68, 86]
diff --git a/21-selection-sort.rb b/21-selection-sort.rb
index e5e7eae..f6fdecb 100644
--- a/21-selection-sort.rb
+++ b/21-selection-sort.rb
@@ -3,10 +3,22 @@
 
 def selection_sort(arr)
   #...
+  i = 0
+  while i < ( arr.size - 1 )
+    j = i + 1
+    while j < arr.size
+      if arr[i] > arr[j]
+        arr[i], arr[j] = arr[j], arr[i]
+      end
+      j += 1
+    end
+    i += 1
+  end
+  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.to_s # 应该是 [1, 7, 9, 42, 46, 46, 68, 77, 86, 91]
diff --git a/22-missing.rb b/22-missing.rb
index 6898714..e7e3af9 100644
--- a/22-missing.rb
+++ b/22-missing.rb
@@ -2,6 +2,20 @@
 
 def find_missing(arr)
   # ...
+  missingArr = []
+  for i in 0..9
+    missing = true
+    for a in arr
+      if a == i
+        missing = false
+        break
+      end
+    end
+    if missing
+      missingArr.push(i)
+    end
+  end
+  missingArr
 end
 
 answer = find_missing( [2,2,1,5,8,4] )
diff --git a/23-hash-max.rb b/23-hash-max.rb
index 6fb227e..4915875 100644
--- a/23-hash-max.rb
+++ b/23-hash-max.rb
@@ -2,6 +2,13 @@
 
 def find_max(hash)
   # ...
+  m = hash["a"]
+  hash.each do |key, value|
+    if m < value
+      m = value
+    end
+  end
+  hash.key(m)
 end
 
 h = {
@@ -15,5 +22,3 @@ def find_max(hash)
 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..6451655 100644
--- a/24-hash-even.rb
+++ b/24-hash-even.rb
@@ -3,7 +3,13 @@
 def find_even_keys(hash)
 
   # ... (请回传一个数组)
-
+  result = {}
+  hash.each do |key, value|
+    if value % 2 == 0
+      result[key] = value
+    end
+  end
+  result.keys
 end
 
 h = {
@@ -17,5 +23,3 @@ 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..158569d 100644
--- a/25-hash-count.rb
+++ b/25-hash-count.rb
@@ -5,6 +5,11 @@ def count(arr)
 
   arr.each do |i|
     # ...
+    if h[i] == nil
+      h[i] = 1
+    else
+      h[i] += 1
+    end
   end
 
   return h # 回传一个 hash
@@ -15,4 +20,3 @@ 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..5f2dcae 100644
--- a/26-hash-filter.rb
+++ b/26-hash-filter.rb
@@ -9,8 +9,15 @@
 ]
 
 # ....
+a = []
+arr.each do |i|
+  if i["age"] >= 18
+    a << i
+  end
+end
+a.sort! { |x, y| x["age"] <=> y["age"] }
 
-puts "所有成年人，并由小到大: _________"
+puts "所有成年人，并由小到大: #{a}"
 
 # 答案应该是
 #[
diff --git a/27-class.rb b/27-class.rb
index 8cec2c9..a4db247 100644
--- a/27-class.rb
+++ b/27-class.rb
@@ -1,5 +1,10 @@
 class Person
   # ...
+  attr_accessor :first_name, :last_name
+
+  def greet
+    puts "Hello, #{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..8d0c12f 100644
--- a/28-word-count.rb
+++ b/28-word-count.rb
@@ -3,3 +3,15 @@
 doc = File.read("wordcount.txt")
 
 # ...
+arr = doc.split("")
+h = {}
+
+arr.each do |wd|
+  if h[d] == nil
+    h[d] = 1
+  else
+    h[d] += 1
+  end
+end
+
+puts h
diff --git a/29-todos.rb b/29-todos.rb
index 0bddde2..ad4494c 100644
--- a/29-todos.rb
+++ b/29-todos.rb
@@ -18,16 +18,24 @@
   if command == "add"
     print "请输入代办事项: "
     # ...
+    newTodo = gets.chomp
+    todos.push(newTodo)
   elsif command == "remove"
     print "请输入要删除的编号: "
     # ...
+    i = gets.chomp.to_i
+    todos.delete_at(i)
   elsif command == "save"
     puts "存盘离开"
-
     # ...
+    File.open("todos.txt", "w+") do |f|
+      todos.each do |line|
+        f << line
+        f << "\n"
+      end
+    end
     break;
   else
     puts "看不懂，请再输入一次"
   end
 end
-
diff --git a/todos.txt b/todos.txt
index 4757e85..840bb11 100644
--- a/todos.txt
+++ b/todos.txt
@@ -1,4 +1,4 @@
 Buy book
 Go Shopping
-Walk
-Gogo
+Ruby on Rails
+gogo