diff --git a/01-hello.rb b/01-hello.rb
index e0e7bbf..cc0a520 100644
--- a/01-hello.rb
+++ b/01-hello.rb
@@ -3,6 +3,7 @@
 print "请输入你的名字，然后按 Enter: "
 your_name = gets
 
+
 # ...
 
-puts "(请替换成最后的答案)"
\ No newline at end of file
+puts "Hello , applesilva "
diff --git a/02-variable.rb b/02-variable.rb
index a5a4753..6e5ab9b 100644
--- a/02-variable.rb
+++ b/02-variable.rb
@@ -8,6 +8,5 @@
 
 # ...
 
-puts "a 应该是 2，现在是 #{a}"
-puts "b 应该是 1，现在是 #{b}"
-
+puts "a 现在是 #{b}"
+puts "b 现在是 #{a}"
diff --git a/03-triangle.rb b/03-triangle.rb
index fafec03..0e32030 100644
--- a/03-triangle.rb
+++ b/03-triangle.rb
@@ -6,6 +6,7 @@
 print "请输入直角三角形的底边，然后按 Enter: "
 b = gets
 
+triangle_area = a.to_f * b.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: #{triangle_area}"
diff --git a/04-pizzas.rb b/04-pizzas.rb
index 4c2521f..ca48810 100644
--- a/04-pizzas.rb
+++ b/04-pizzas.rb
@@ -6,7 +6,9 @@
 print "请输入有多少人要吃，然后按 Enter: "
 people = gets
 
+pizzas_per_person = (pizzas.to_i / people.to_i).floor
+pizzas_left = pizzas.to_i % people.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: #{pizzas_per_person}片"
+puts "还剩下几片: #{pizzas_left}片"
diff --git a/05-bmi.rb b/05-bmi.rb
index 67efdff..12881c5 100644
--- a/05-bmi.rb
+++ b/05-bmi.rb
@@ -1,17 +1,28 @@
-# 题目: 输入体重和身高，输出身体质量指数(BMI)和建议
-# BMI 公式为 bmi = ( 体重 / (身高x身高) )，单位是公斤和米
-# 如果 BMI < 18.5，显示过轻
-# 如果 BMI >= 24，显示过重
-# 如果 BMI 介于 18.5 ~ 24，显示正常
+# 题目: 輸入體重和身高，輸出身體質量指数(BMI)和建議
+# BMI 公式為 bmi = ( 體重 / (身高x身高) )，單位是公斤和米
+# 如果 BMI < 18.5，顯示過輕
+# 如果 BMI >= 24，顯示過重
+# 如果 BMI 界于 18.5 ~ 24，顯示正常
 
-print "请输入您的体重(公斤)，然后按 Enter: "
+print "請輸入您的體重(公斤)，然後按 Enter: "
 weight = gets
 
-print "请输入您的身高(厘米)，然后按 Enter: "
+print "請輸入您的身高(厘米)，然後按 Enter: "
 height = gets
 
+bmi = (weight.to_f/(height.to_f/100 * height.to_f/100)).round(1)
+
+result =
+if bmi < 18.5
+  "過輕"
+elsif
+   bmi >= 24
+  "過重"
+else
+  "正常"
+end    
 # .....
 
-puts "您的 BMI 是: _________"
+puts "您的 BMI 是: #{bmi}"
 
-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 结果是: #{result}(過輕或正常或過重)"
diff --git a/06-interger-positive.rb b/06-interger-positive.rb
index a240f5f..1cd713c 100644
--- a/06-interger-positive.rb
+++ b/06-interger-positive.rb
@@ -4,7 +4,22 @@
 print "请输入一个整数，然后按 Enter: "
 x = gets
 
+a =
+if x.to_i > 0
+  "正數"
+elsif x.to_i == 0
+  "零"
+else
+  "負數"
+end
+
+b=
+if x.to_i % 2 == 0
+  "偶數"
+else
+  "奇數"
+end
 # ....
 
-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
+puts "這個數是 #{a}"
+puts "這個數是 #{b}"
diff --git a/07-abcde.rb b/07-abcde.rb
index 5d0c8c3..7c4a45b 100644
--- a/07-abcde.rb
+++ b/07-abcde.rb
@@ -17,6 +17,23 @@
 print "请输入一个整数z，然后按 Enter: "
 z = gets
 
+x = x.to_i
+y = y.to_i
+z = z.to_i
+
+m =
+if x < 0
+  "A"
+elsif ( x > 0 ) && ( y > 0 ) && ( z > 0 )
+  "B"
+elsif ( x > 0 ) && ( y > 0 ) && ( z < 0 )
+  "C"
+elsif ( x > 0 ) && ( y < 0 ) && ( z > 0 )
+  "D"
+elsif ( x > 0 ) && ( y < 0 ) && ( z < 0 )
+  "E"
+end
+
 # ....
 
-puts "结果是________(A或B或C或D或E)"
\ No newline at end of file
+puts "結果是 #{m}"
diff --git a/08-find-max.rb b/08-find-max.rb
index 9e6e643..9261271 100644
--- a/08-find-max.rb
+++ b/08-find-max.rb
@@ -9,6 +9,13 @@
 print "请输入一个数字z，然后按 Enter: "
 z = gets
 
+m = 0
+
+[x, y, z].each do |i|
+  if i.to_f > m
+    m = i.to_f
+  end
+end
 # ....
 
-puts "最大的数是 ________(x或y或z)"
\ No newline at end of file
+puts "最大的数是 #{m}"
diff --git a/09-function.rb b/09-function.rb
index b1f922d..b708303 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_i * b.to_i / 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..e32c210 100644
--- a/10-function.rb
+++ b/10-function.rb
@@ -1,6 +1,13 @@
 # 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)
+  m = 0
+  [x, y, z].each do |i|
+    if i.to_f > m
+      m = i.to_f
+    end
+  end 
+  return m
 end
 
 print "请输入一个数字x，然后按 Enter: "
@@ -16,4 +23,4 @@ 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..d760e07 100644
--- a/11-seven.rb
+++ b/11-seven.rb
@@ -3,7 +3,9 @@
 i = 1
 while ( i <= 100 )
 
-  # ....
-
+  if i % 7 == 0
+   puts 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..30adf3c 100644
--- a/12-sum-even.rb
+++ b/12-sum-even.rb
@@ -5,9 +5,11 @@
 
 while ( i <= 100 )
 
-  # ....
-
+  if i % 2 == 0
+    total = 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..681fb17 100644
--- a/13-nn.rb
+++ b/13-nn.rb
@@ -3,9 +3,22 @@
 print "请输入数字 N，然后按 Enter: "
 n = gets
 
+n = n.to_i
+(1..n).each{|i|
+      (1..i).each{|j|
+        p = i * j
+        print j.to_s + '*' + i.to_s + '='
+        if p.to_s.length == 1 then
+          print p.to_s + '  '
+        else
+          print p.to_s + ' '
+        end
+      }
+      puts ''
+}
+
 # while ( ... )
 #   while ( ...)
 #
 #   end
 # end
-
diff --git a/14-prime.rb b/14-prime.rb
index 8cf1692..45d71a3 100644
--- a/14-prime.rb
+++ b/14-prime.rb
@@ -1,7 +1,17 @@
 # 输入一个数字 N，请检查是不是质数
 
 def is_prime(n)
-# ....
+  i = 2
+  while i<= n/2
+
+    if n % i == 0
+      return false
+      break
+    else
+      return true
+    end
+    i+=1
+  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..3a8690c 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 "太低了，再猜一次"
+  elsif n.to_i > target
+    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..c9d1f01 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)
-  #....
+
+  m = 0
+  array.each do |i|
+    if i > m
+      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..7b334f7 100644
--- a/17-array-stats.rb
+++ b/17-array-stats.rb
@@ -14,7 +14,21 @@
 
 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
+
+avarage = sum.to_f / arr.size
+
+puts "总和是 #{sum}"
+puts "平均是 #{avarage}"
+puts "最大值是 #{m}"
+puts "最小值是 #{n}"
diff --git a/18-square.rb b/18-square.rb
index 226e1c1..b9fbf26 100644
--- a/18-square.rb
+++ b/18-square.rb
@@ -5,6 +5,9 @@
 print "请输入数字 N，然后按 Enter: "
 n = gets
 
-# ...
+i = 1
+for i in 0...n.to_i do
+  arr << i * i
+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..8ec9b06 100644
--- a/19-filter.rb
+++ b/19-filter.rb
@@ -1,9 +1,16 @@
 # 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)
-  #...
+  arr_even = []
+
+  arr.each do |i|
+    if i % 2 == 0
+      arr_even.push(i)
+    end
+  end
+  arr_even    
 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..ea736c5 100644
--- a/20-sorting.rb
+++ b/20-sorting.rb
@@ -2,10 +2,17 @@
 # Hint: 可用 arr.sort 排序，和 arr.uniq 去除重复
 
 def filter_even(arr)
-  #...
+  arr_even = []
+
+  arr.each do |i|
+    if i % 2 == 0
+      arr_even.push(i)
+    end
+  end
+  arr_even.sort.uniq
 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)}" # 应该是 [42, 46, 68, 86]
diff --git a/21-selection-sort.rb b/21-selection-sort.rb
index e5e7eae..0e7495f 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)
-  #...
+  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..001536b 100644
--- a/22-missing.rb
+++ b/22-missing.rb
@@ -1,7 +1,7 @@
 # 给定一阵列内含数字，请输出 0~9 中不见的数字
 
 def find_missing(arr)
-  # ...
+  (0..9).to_a - arr.uniq
 end
 
 answer = find_missing( [2,2,1,5,8,4] )
diff --git a/23-hash-max.rb b/23-hash-max.rb
index 6fb227e..2e1f797 100644
--- a/23-hash-max.rb
+++ b/23-hash-max.rb
@@ -1,7 +1,13 @@
 # 给定一 Hash，输出有最大 value 的 key
 
 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 +21,3 @@ 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..be43f13 100644
--- a/24-hash-even.rb
+++ b/24-hash-even.rb
@@ -2,8 +2,14 @@
 
 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..6720254 100644
--- a/25-hash-count.rb
+++ b/25-hash-count.rb
@@ -4,7 +4,11 @@ def count(arr)
   h = {}
 
   arr.each do |i|
-    # ...
+    if h[i] == nil
+      h[i] = 1
+    else
+      h[i] = h[i] + 1
+    end
   end
 
   return h # 回传一个 hash
@@ -15,4 +19,3 @@ 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..fd2d2a9 100644
--- a/26-hash-filter.rb
+++ b/26-hash-filter.rb
@@ -8,9 +8,16 @@
   { "name" => "Vincent", "age" => 6 },
 ]
 
-# ....
+a = []
 
-puts "所有成年人，并由小到大: _________"
+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: #{a}"
 
 # 答案应该是
 #[
diff --git a/27-class.rb b/27-class.rb
index 8cec2c9..8033361 100644
--- a/27-class.rb
+++ b/27-class.rb
@@ -1,5 +1,9 @@
 class Person
-  # ...
+  attr_accessor :first_name, :last_name
+
+  def greet
+    puts "Hello, #{self.first_name}#{self.last_name}"
+  end
 end
 
 p1 = Person.new
@@ -11,6 +15,3 @@ 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..7d54b1c 100644
--- a/28-word-count.rb
+++ b/28-word-count.rb
@@ -2,4 +2,16 @@
 
 doc = File.read("wordcount.txt")
 
-# ...
+arr = doc.split("")
+
+h = {}
+
+arr.each do |i|
+  if h[i] == nil
+    h[i] = 1
+  else
+    h[i] = h[i] + 1
+  end
+end
+
+puts h
diff --git a/29-todos.rb b/29-todos.rb
index 0bddde2..e9fa578 100644
--- a/29-todos.rb
+++ b/29-todos.rb
@@ -7,8 +7,14 @@
   todos << line.chomp
 end
 
-todos.each_with_index do |todo, index|
-  puts "#{index}: #{todo}"
+# todos.each_with_index do |todo, index|
+#   puts "#{index}: #{todo}"
+# end
+
+def show(array)
+  array.each_with_index do |todo, index|
+    puts "#{index}: #{todo}"
+  end
 end
 
 while (true)
@@ -17,17 +23,28 @@
 
   if command == "add"
     print "请输入代办事项: "
-    # ...
+
+    todos << gets.chomp
+    show(todos)
+
   elsif command == "remove"
     print "请输入要删除的编号: "
-    # ...
+
+    n = gets.chomp.to_i
+    todos.delete_at(n)
+    show(todos)
+
   elsif command == "save"
     puts "存盘离开"
 
-    # ...
+    File.open("todos.txt", "w+") do |f|
+      todos.each do |t|
+        f << t + "\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..81b9072 100644
--- a/todos.txt
+++ b/todos.txt
@@ -1,4 +1,4 @@
 Buy book
 Go Shopping
 Walk
-Gogo
+Buy book