diff --git a/01-hello.rb b/01-hello.rb
index e0e7bbf..e4e56e9 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 your_name
diff --git a/02-variable.rb b/02-variable.rb
index a5a4753..2821710 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 应该是 2，现在是 #{b}"
+puts "b 应该是 1，现在是 #{a}"
diff --git a/03-triangle.rb b/03-triangle.rb
index fafec03..d4ed7bb 100644
--- a/03-triangle.rb
+++ b/03-triangle.rb
@@ -5,7 +5,7 @@
 
 print "请输入直角三角形的底边，然后按 Enter: "
 b = gets
-
+t = (a.to_i * b.to_i)/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:#{t}"
diff --git a/04-pizzas.rb b/04-pizzas.rb
index 4c2521f..8eff592 100644
--- a/04-pizzas.rb
+++ b/04-pizzas.rb
@@ -7,6 +7,7 @@
 people = gets
 
 # .....
-
-puts "每人可分得几片: _________ 片"
-puts "还剩下几片: _________ 片"
\ No newline at end of file
+t1= pizzas.to_i / people.to_i
+t2= pizzas.to_i % people.to_i
+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..cd2e5cc 100644
--- a/05-bmi.rb
+++ b/05-bmi.rb
@@ -11,7 +11,18 @@
 height = gets
 
 # .....
+bmi = weight.to_f / (height.to_f * height.to_f)
 
-puts "您的 BMI 是: _________"
 
-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: #{bmi}"
+
+if bmi<18.5
+    r = "过轻"
+  elsif bmi>=24
+    r = "过重"
+  else
+    r = "正常"
+end
+
+puts "您的 BMI 结果是: #{r}"
diff --git a/06-interger-positive.rb b/06-interger-positive.rb
index a240f5f..2b1efe3 100644
--- a/06-interger-positive.rb
+++ b/06-interger-positive.rb
@@ -3,8 +3,22 @@
 
 print "请输入一个整数，然后按 Enter: "
 x = gets
-
+t = x.to_i
 # ....
 
-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 t > 0
+    s = "正数"
+  elsif t < 0
+    s = "负数"
+  else
+    s = "0"
+end
+
+if t%2 == 0
+  y = "偶数"
+else
+  y = "奇数"
+end
+
+puts "这个数是#{s}"
+puts "这个数是#{y}"
diff --git a/07-abcde.rb b/07-abcde.rb
index 5d0c8c3..22f0805 100644
--- a/07-abcde.rb
+++ b/07-abcde.rb
@@ -18,5 +18,22 @@
 z = gets
 
 # ....
+x1 = x.to_i
+x2 = y.to_i
+x3 = z.to_i
 
-puts "结果是________(A或B或C或D或E)"
\ No newline at end of file
+if x1 < 0
+  r = "A"
+elsif x1 >0 && x2 >0 && x3 >0
+  r = "B"
+elsif x1 >0 && x2 >0 && x3 <0
+  r = "C"
+elsif x2<0 && x3 >0
+  r = "D"
+elsif x2<0 && x3<0
+  r = "E"
+end
+
+
+
+puts "结果是#{r}"
diff --git a/08-find-max.rb b/08-find-max.rb
index 9e6e643..988fd40 100644
--- a/08-find-max.rb
+++ b/08-find-max.rb
@@ -11,4 +11,17 @@
 
 # ....
 
-puts "最大的数是 ________(x或y或z)"
\ No newline at end of file
+x1 = x.to_i
+y1 = y.to_i
+z1 = z.to_i
+if x1 >= y1 &&  x1 >= z1
+   r= x1
+elsif y1 >= x1 && y1>= z1
+   r= y1
+
+else
+   r= z1
+end
+
+
+puts "最大的数是#{r}"
diff --git a/09-function.rb b/09-function.rb
index b1f922d..0e03d84 100644
--- a/09-function.rb
+++ b/09-function.rb
@@ -1,15 +1,15 @@
 # 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)
-  # ....
+  (b*a)/2
 end
 
 print "请输入直角三角形的高，然后按 Enter: "
-a = gets
-
+a = gets().to_i
 print "请输入直角三角形的底边，然后按 Enter: "
-b = gets
+b = gets().to_i
+
 
-answer = calculate_area(a,b)
 
-puts "直角三角形的面积是: #{answer}"
\ No newline at end of file
+  answer = calculate_area(a,b)
+puts "直角三角形的面积是: #{answer}"
diff --git a/10-function.rb b/10-function.rb
index bb450fb..4ca8d78 100644
--- a/10-function.rb
+++ b/10-function.rb
@@ -1,19 +1,29 @@
 # 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 >= y &&  x >= z
+     r= x
+  elsif y>= x && y>= z
+     r= y
+
+  else
+     r= z
+  end
 end
 
 print "请输入一个数字x，然后按 Enter: "
-x = gets
+x = gets().to_i
 
 print "请输入一个数字y，然后按 Enter: "
-y = gets
+y = gets().to_i
 
 print "请输入一个数字z，然后按 Enter: "
-z = gets
+z = gets().to_i
 
 # ....
 
+
+
 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..44a2257 100644
--- a/11-seven.rb
+++ b/11-seven.rb
@@ -2,8 +2,9 @@
 
 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..56eb4cd 100644
--- a/12-sum-even.rb
+++ b/12-sum-even.rb
@@ -5,9 +5,10 @@
 
 while ( i <= 100 )
 
-  # ....
-
-  i+=1
+  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..465daf6 100644
--- a/13-nn.rb
+++ b/13-nn.rb
@@ -1,11 +1,13 @@
 # 题目: 输入一个数字 N，输出 N * N 乘法表
 
 print "请输入数字 N，然后按 Enter: "
-n = gets
-
-# while ( ... )
-#   while ( ...)
-#
-#   end
-# end
-
+n = gets.to_i
+i = 1
+ while ( i <= n )
+   j = i
+   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..6deff02 100644
--- a/14-prime.rb
+++ b/14-prime.rb
@@ -1,13 +1,20 @@
 # 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)
+    while n % i == 0
+      return false
+    end
+    i+=1
+  end
+  return true
 end
 
 print "请输入数字 N，然后按 Enter: "
-n = gets
+n = gets.to_i
 
-if is_prime(n.to_i)
+if is_prime(n)
   puts "这是质数"
 else
   puts "这不是质数"
diff --git a/15-guess-number.rb b/15-guess-number.rb
index 48f9dca..a64986d 100644
--- a/15-guess-number.rb
+++ b/15-guess-number.rb
@@ -5,13 +5,14 @@
 while (true)
   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 "太低了，再猜一次"
+elsif n.to_i >target
+  puts "太高了，再猜一次"
+end
   if 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..7b6fd47 100644
--- a/16-array-sum.rb
+++ b/16-array-sum.rb
@@ -1,11 +1,10 @@
 # 给定一阵列内含数字，输出最大值
 
 def find_max(array)
-  #....
+  array.max()
 end
 
-arr = [8, 12, 36, 53, 9, 75, 3, 71, 59, 88]
+arr = [8, 12, 36, 53, 9, 158, 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..574dbd7 100644
--- a/17-array-stats.rb
+++ b/17-array-stats.rb
@@ -12,9 +12,28 @@
   end
 end
 
-puts arr.to_s
+max = arr[0]
+min = arr[0]
+sum = 0
+
+arr.each do |i|
+    if max < i
+      max = i
+    end
+
+    if min > i
+      min = i
+    end
+
+    sum = sum + i
+end
 
-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 arr.to_s
+puts "总和是 #{sum}"
+puts "平均是 #{sum/arr.size}"
+puts "最大值是 #{max}"
+puts "最小值是#{min}"
diff --git a/18-square.rb b/18-square.rb
index 226e1c1..b9fda86 100644
--- a/18-square.rb
+++ b/18-square.rb
@@ -3,8 +3,12 @@
 arr = []
 
 print "请输入数字 N，然后按 Enter: "
-n = gets
-
+n = gets.to_i
+i = 1
 # ...
+while i<=n
+  arr<<(i-1)*(i-1)
+  i+=1
 
-puts arr.to_s
\ No newline at end of file
+end
+puts arr.to_s
diff --git a/19-filter.rb b/19-filter.rb
index ef7e515..c4c69bf 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)
-  #...
+  array = []
+  arr.each do |i|
+    if i % 2 == 0
+        array<<i
+    end
+  end
+  return array
 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..acd2259 100644
--- a/20-sorting.rb
+++ b/20-sorting.rb
@@ -2,10 +2,16 @@
 # Hint: 可用 arr.sort 排序，和 arr.uniq 去除重复
 
 def filter_even(arr)
-  #...
+  array = []
+  arr.each do |i|
+    if i % 2 == 0
+        array<<i
+    end
+  end
+  return array.uniq.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..76af2d4 100644
--- a/21-selection-sort.rb
+++ b/21-selection-sort.rb
@@ -2,11 +2,16 @@
 # https://zh.wikipedia.org/wiki/选择排序
 
 def selection_sort(arr)
-  #...
+  (0...arr.length).each do |i|
+    min,index = arr[i],i
+    (i...arr.length).each{|j|min,index = arr[j], j if arr[j] <min}
+    arr[i],arr[index] = arr[index],arr[i]
+  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..1a43b35 100644
--- a/22-missing.rb
+++ b/22-missing.rb
@@ -1,7 +1,11 @@
 # 给定一阵列内含数字，请输出 0~9 中不见的数字
 
 def find_missing(arr)
-  # ...
+  missing_arr = []
+  (0..9).each do |i|
+    missing_arr << i unless arr.include?(i)
+  end
+  missing_arr
 end
 
 answer = find_missing( [2,2,1,5,8,4] )
diff --git a/23-hash-max.rb b/23-hash-max.rb
index 6fb227e..d0017d8 100644
--- a/23-hash-max.rb
+++ b/23-hash-max.rb
@@ -1,7 +1,11 @@
 # 给定一 Hash，输出有最大 value 的 key
 
 def find_max(hash)
-  # ...
+  hash.each do |key, value|
+  return  key if value== hash.values.max
+
+  end
+  
 end
 
 h = {
@@ -15,5 +19,3 @@ 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..1046f0a 100644
--- a/24-hash-even.rb
+++ b/24-hash-even.rb
@@ -1,9 +1,12 @@
 # 给定一 Hash，输出 value 是偶数的 keys
 
 def find_even_keys(hash)
+  result= []
+  hash.each do |key, value|
+   result << key if value%2 == 0
 
-  # ... (请回传一个数组)
-
+  end
+result
 end
 
 h = {
@@ -17,5 +20,3 @@ 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..eb828b8 100644
--- a/25-hash-count.rb
+++ b/25-hash-count.rb
@@ -4,7 +4,8 @@ def count(arr)
   h = {}
 
   arr.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..3a43f46 100644
--- a/26-hash-filter.rb
+++ b/26-hash-filter.rb
@@ -7,10 +7,17 @@
   { "name" => "Steven", "age" => 22 },
   { "name" => "Vincent", "age" => 6 },
 ]
+def filter(arr)
+  result_arr = []
+  arr.each do |h|
+    if h["age"]>=18
+      result_arr.push(h)
+    end
+  end
+  result_arr.sort_by{|i| i["age"]}
 
-# ....
-
-puts "所有成年人，并由小到大: _________"
+end
+puts "所有成年人，并由小到大:#{filter(arr)} "
 
 # 答案应该是
 #[
diff --git a/27-class.rb b/27-class.rb
index 8cec2c9..a3f690e 100644
--- a/27-class.rb
+++ b/27-class.rb
@@ -1,5 +1,11 @@
 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 +17,3 @@ 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..652dc59 100644
--- a/28-word-count.rb
+++ b/28-word-count.rb
@@ -2,4 +2,10 @@
 
 doc = File.read("wordcount.txt")
 
-# ...
+words = doc.scan(/\w+/)
+result = {}
+words.each do |i|
+  result[i] = words.count(i)
+
+end
+puts result
diff --git a/29-todos.rb b/29-todos.rb
index 0bddde2..4b266e4 100644
--- a/29-todos.rb
+++ b/29-todos.rb
@@ -17,17 +17,23 @@
 
   if command == "add"
     print "请输入代办事项: "
-    # ...
+     add = gets
+     todos << add
   elsif command == "remove"
     print "请输入要删除的编号: "
-    # ...
+     remove = gets
+     todos.delete_at(remove.to_i)
   elsif command == "save"
     puts "存盘离开"
+    target = File.open("todos.txt", "w+")
+          for i in todos
+            target.write(i+"\n")
+          
+          end
+          target.close()
 
-    # ...
     break;
   else
     puts "看不懂，请再输入一次"
   end
 end
-
diff --git a/todos.txt b/todos.txt
index 4757e85..59b74e5 100644
--- a/todos.txt
+++ b/todos.txt
@@ -1,4 +1,5 @@
 Buy book
 Go Shopping
-Walk
 Gogo
+To cut hair
+