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..484f6f8 100644
--- a/02-variable.rb
+++ b/02-variable.rb
@@ -6,8 +6,11 @@
 puts "a 是 #{a}"
 puts "b 是 #{b}"
 
+a = a + b
+b = a - b
+a = a - b
+
 # ...
 
 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..0d10514 100644
--- a/03-triangle.rb
+++ b/03-triangle.rb
@@ -7,5 +7,6 @@
 b = gets
 
 # .....
+area = 0.5 * a.to_f * b.to_f
 
-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: #{area}"
diff --git a/04-pizzas.rb b/04-pizzas.rb
index 4c2521f..4b4045f 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
 
+a = pizzas.to_i % people.to_i
+b = (pizzas.to_i - a) / 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: #{b} 片"
+puts "还剩下几片: #{a} 片"
diff --git a/05-bmi.rb b/05-bmi.rb
index 67efdff..893078d 100644
--- a/05-bmi.rb
+++ b/05-bmi.rb
@@ -10,8 +10,18 @@
 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
+
+if bmi < 18.5
+  result = '过轻'
+elsif bmi < 24.0
+  result = '正常'
+else
+  result = '过重'
+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}"
diff --git a/06-interger-positive.rb b/06-interger-positive.rb
index a240f5f..ac3b94a 100644
--- a/06-interger-positive.rb
+++ b/06-interger-positive.rb
@@ -4,7 +4,21 @@
 print "请输入一个整数，然后按 Enter: "
 x = gets
 
+if x.to_i > 0
+  result1 = '正数'
+elsif x.to_i < 0
+  result1 = '负数'
+else
+  result1 = '零'
+end
+
+if x.to_f % 2 ==0
+  result2 = '偶数'
+else
+  result2 = '奇数'
+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 "这个数是 #{result1}"
+puts "这个数是 #{result2}"
diff --git a/07-abcde.rb b/07-abcde.rb
index 5d0c8c3..683f42f 100644
--- a/07-abcde.rb
+++ b/07-abcde.rb
@@ -17,6 +17,24 @@
 print "请输入一个整数z，然后按 Enter: "
 z = gets
 
+if x.to_i < 0
+  result = "A"
+elsif x.to_i > 0
+  if y.to_i > 0
+    if z.to_i > 0
+      result = "B"
+    elsif z.to_i <0
+      result = "C"
+    end
+  elsif y.to_i < 0
+    if z.to_i > 0
+      result = "D"
+    elsif z.to_i <0
+      result = "E"
+    end
+  end
+end
+
 # ....
 
-puts "结果是________(A或B或C或D或E)"
\ No newline at end of file
+puts "结果是 #{result}"
diff --git a/08-find-max.rb b/08-find-max.rb
index 9e6e643..ea43084 100644
--- a/08-find-max.rb
+++ b/08-find-max.rb
@@ -9,6 +9,19 @@
 print "请输入一个数字z，然后按 Enter: "
 z = gets
 
+if x.to_f >= y.to_f
+  if x.to_f >= z.to_f
+    result = x
+  else
+    result = z
+  end
+else
+  if y.to_f >= z.to_f
+    result = y
+  else
+    result = z
+  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 #{result}"
diff --git a/09-function.rb b/09-function.rb
index b1f922d..3225c1f 100644
--- a/09-function.rb
+++ b/09-function.rb
@@ -1,7 +1,8 @@
 # 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)
-  # ....
+  area = 0.5 * a.to_f * b.to_f
+  return area
 end
 
 print "请输入直角三角形的高，然后按 Enter: "
@@ -12,4 +13,4 @@ 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..38d9743 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)
+  if x.to_f >= y.to_f
+    if x.to_f >= z.to_f
+      result = x
+    else
+      result = z
+    end
+  else
+    if y.to_f >= z.to_f
+      result = y
+    else
+      result = z
+    end
+  end
+  return result
 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..97d5e96 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..575911d 100644
--- a/12-sum-even.rb
+++ b/12-sum-even.rb
@@ -5,9 +5,11 @@
 
 while ( i <= 100 )
 
-  # ....
+  if i % 2 ==0
+    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..ea69134 100644
--- a/13-nn.rb
+++ b/13-nn.rb
@@ -2,10 +2,14 @@
 
 print "请输入数字 N，然后按 Enter: "
 n = gets
-
-# while ( ... )
-#   while ( ...)
-#
-#   end
-# end
-
+i = 1
+while ( i <= n.to_i )
+  j = 1
+  while ( j <= i)
+    result = i * j
+    print "#{j} x #{i} = #{result}  "
+    j += 1
+  end
+  print "\n"
+  i +=1
+end
diff --git a/14-prime.rb b/14-prime.rb
index 8cf1692..6d26543 100644
--- a/14-prime.rb
+++ b/14-prime.rb
@@ -1,7 +1,16 @@
 # 输入一个数字 N，请检查是不是质数
 
 def is_prime(n)
-# ....
+  i = 2
+  result = true
+  while i < n.to_i
+    if n.to_i % i == 0
+      result = false
+      break
+    end
+    i +=1
+  end
+  return result
 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..42f221f 100644
--- a/15-guess-number.rb
+++ b/15-guess-number.rb
@@ -8,10 +8,13 @@
 
   #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! "
+  if 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"
+  elsif n.to_i == target
+    puts "恭喜猜中啦!"
     break
   end
 
-end
\ No newline at end of file
+end
diff --git a/16-array-sum.rb b/16-array-sum.rb
index 9b4910b..64d1e02 100644
--- a/16-array-sum.rb
+++ b/16-array-sum.rb
@@ -1,11 +1,11 @@
 # 给定一阵列内含数字，输出最大值
 
 def find_max(array)
-  #....
+  result = array.max
+  return result 
 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..1e8a42a 100644
--- a/17-array-stats.rb
+++ b/17-array-stats.rb
@@ -12,9 +12,14 @@
   end
 end
 
+suma = arr.inject(0, :+)
+avga = suma.to_f / arr.size
+maxa = arr.max
+mina = 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 #{suma}"
+puts "平均是 #{avga}"
+puts "最大值是 #{maxa}"
+puts "最小值是 #{mina}"
diff --git a/18-square.rb b/18-square.rb
index 226e1c1..6b8147e 100644
--- a/18-square.rb
+++ b/18-square.rb
@@ -5,6 +5,10 @@
 print "请输入数字 N，然后按 Enter: "
 n = gets
 
-# ...
+i = 0
+while i <= n.to_i
+  arr << i**2
+  i += 1
+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..015f463 100644
--- a/19-filter.rb
+++ b/19-filter.rb
@@ -1,9 +1,15 @@
 # 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)
-  #...
+  arra = []
+  arr.each do |i|
+    if i % 2 == 0
+      arra << i
+    end
+  end
+  return arra
 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..3e31016 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)
-  #...
+  arra = []
+  arra = arr.uniq.sort
+  return arra
 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 arr.to_s
+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..d978be8 100644
--- a/21-selection-sort.rb
+++ b/21-selection-sort.rb
@@ -2,11 +2,21 @@
 # https://zh.wikipedia.org/wiki/选择排序
 
 def selection_sort(arr)
-  #...
+   n = arr.size
+   for i in 0..(n - 1)
+     for j in (i + 1)..(n - 1)
+       if arr[i] >= arr[j]
+         tem = arr[j]
+         arr[j] = arr[i]
+         arr[i] = tem 
+       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.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..3000f45 100644
--- a/22-missing.rb
+++ b/22-missing.rb
@@ -1,7 +1,13 @@
 # 给定一阵列内含数字，请输出 0~9 中不见的数字
 
 def find_missing(arr)
-  # ...
+  arra = []
+  for i in 0..9
+    if not arr.include? i
+      arra << i
+    end
+  end
+  return arra
 end
 
 answer = find_missing( [2,2,1,5,8,4] )
diff --git a/23-hash-max.rb b/23-hash-max.rb
index 6fb227e..12bed97 100644
--- a/23-hash-max.rb
+++ b/23-hash-max.rb
@@ -1,7 +1,7 @@
 # 给定一 Hash，输出有最大 value 的 key
 
 def find_max(hash)
-  # ...
+  return hash.key(hash.values.max)
 end
 
 h = {
@@ -15,5 +15,3 @@ 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..dfed896 100644
--- a/24-hash-even.rb
+++ b/24-hash-even.rb
@@ -2,7 +2,15 @@
 
 def find_even_keys(hash)
 
-  # ... (请回传一个数组)
+  arr = []
+
+  hash.each do |k, v|
+    if v % 2 == 0
+      arr << k
+    end
+  end
+
+  return arr 
 
 end
 
@@ -17,5 +25,3 @@ 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..fdd73af 100644
--- a/25-hash-count.rb
+++ b/25-hash-count.rb
@@ -3,8 +3,10 @@
 def count(arr)
   h = {}
 
-  arr.each do |i|
-    # ...
+  arra = arr.uniq
+
+  arra.each do |i|
+    h[i] = arr.count(i)
   end
 
   return h # 回传一个 hash
@@ -15,4 +17,3 @@ 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..d68e1e9 100644
--- a/26-hash-filter.rb
+++ b/26-hash-filter.rb
@@ -8,9 +8,17 @@
   { "name" => "Vincent", "age" => 6 },
 ]
 
-# ....
+arra = []
 
-puts "所有成年人，并由小到大: _________"
+arr.each do |h|
+    if h["age"] >= 18
+      arra << h
+    end
+end
+
+result = arra.sort_by { |h| h["age"]  }
+
+puts "所有成年人，并由小到大: #{result}"
 
 # 答案应该是
 #[
diff --git a/27-class.rb b/27-class.rb
index 8cec2c9..53224ba 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 "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..285b5bd 100644
--- a/28-word-count.rb
+++ b/28-word-count.rb
@@ -2,4 +2,17 @@
 
 doc = File.read("wordcount.txt")
 
-# ...
+newdoc = doc.gsub(/(n['’]t\b)|\p{P}/, '\1')
+
+arr = newdoc.split
+
+arra = arr.uniq
+
+h = {}
+
+arra.each do |a|
+  h[a] = arr.count(a)
+end
+
+puts h
+puts h["ac"]
diff --git a/29-todos.rb b/29-todos.rb
index 0bddde2..b4350f2 100644
--- a/29-todos.rb
+++ b/29-todos.rb
@@ -17,17 +17,26 @@
 
   if command == "add"
     print "请输入代办事项: "
-    # ...
+    todos << gets.chomp
+    todos.each_with_index do |todo, index|
+      puts "#{index}: #{todo}"
+    end
   elsif command == "remove"
     print "请输入要删除的编号: "
-    # ...
+    todos.delete_at(gets.chomp.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
-