diff --git a/01-hello.rb b/01-hello.rb
index e0e7bbf..fe34e8d 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..00ad6ba 100644
--- a/02-variable.rb
+++ b/02-variable.rb
@@ -8,6 +8,8 @@
 
 # ...
 
+a = b
+c = a
+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..30d1d8c 100644
--- a/03-triangle.rb
+++ b/03-triangle.rb
@@ -8,4 +8,4 @@
 
 # .....
 
-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}"
diff --git a/04-pizzas.rb b/04-pizzas.rb
index 4c2521f..340791d 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} 片"
+puts "还剩下几片: #{pizzas.to_i % people.to_i} 片"
diff --git a/05-bmi.rb b/05-bmi.rb
index 67efdff..dec7be5 100644
--- a/05-bmi.rb
+++ b/05-bmi.rb
@@ -9,9 +9,19 @@
 
 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)
 # .....
 
-puts "您的 BMI 是: _________"
+puts "您的 BMI 是: #{bmi}"
+
+if bmi <18.5
+    a = "过轻"
+
+elsif bmi >= 24
+    a =  "过重"
+
+  else
+    a = "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 结果是:#{a}"
diff --git a/06-interger-positive.rb b/06-interger-positive.rb
index a240f5f..e83acc2 100644
--- a/06-interger-positive.rb
+++ b/06-interger-positive.rb
@@ -5,6 +5,21 @@
 x = gets
 
 # ....
+if x.to_i> 0
+  a = "正数"
+elsif x.to_i== 0
+  a = "零"
+else
+  a = "负数"
+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
+
+if x.to_i % 2 == 0
+  b = "偶数"
+  else
+  b = "奇数"
+end
+
+
+puts "这个数是 #{a}"
+puts "这个数是 #{b}"
diff --git a/07-abcde.rb b/07-abcde.rb
index 5d0c8c3..e1689a0 100644
--- a/07-abcde.rb
+++ b/07-abcde.rb
@@ -19,4 +19,23 @@
 
 # ....
 
-puts "结果是________(A或B或C或D或E)"
\ No newline at end of file
+
+if x.to_i < 0
+   a = "A"
+ elsif x.to_i > 0
+   if y.to_i > 0
+     if z.to_i > 0
+       a = "B"
+     elsif z.to_i < 0
+       a = "C"
+     end
+   elsif y.to_i < 0
+     if z.to_i > 0
+       a = "D"
+     elsif z.to_i < 0
+       a = "E"
+     end
+   end
+ end
+
+ puts "结果是#{a}"
diff --git a/08-find-max.rb b/08-find-max.rb
index 9e6e643..9450625 100644
--- a/08-find-max.rb
+++ b/08-find-max.rb
@@ -11,4 +11,23 @@
 
 # ....
 
-puts "最大的数是 ________(x或y或z)"
\ No newline at end of file
+a = x.to_f
+ b = y.to_f
+ c = z.to_f
+ 
+ if a >= b
+   if a >= c
+     big = x
+   else
+     big = z
+   end
+ else
+   if b >= c
+     big = y
+   else
+     big = z
+   end
+ end
+ 
+ 
+ puts "最大的数是 #{big}"
diff --git a/09-function.rb b/09-function.rb
index b1f922d..d5efec8 100644
--- a/09-function.rb
+++ b/09-function.rb
@@ -2,6 +2,7 @@
 
 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 +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..00027b7 100644
--- a/10-function.rb
+++ b/10-function.rb
@@ -1,6 +1,25 @@
 # 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)
+    a = x.to_f
+   b = y.to_f
+   c = z.to_f
+
+   if a >= b
+     if a >= c
+       big = x
+     else
+       big = z
+     end
+   else
+     if b >= c
+       big = y
+     else
+       big = z
+     end
+   end
+
+   return big
 end
 
 print "请输入一个数字x，然后按 Enter: "
@@ -16,4 +35,4 @@ 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..5f57f12 100644
--- a/11-seven.rb
+++ b/11-seven.rb
@@ -2,8 +2,8 @@
 
 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..73e3966 100644
--- a/12-sum-even.rb
+++ b/12-sum-even.rb
@@ -4,10 +4,12 @@
 total = 0
 
 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..9408d05 100644
--- a/13-nn.rb
+++ b/13-nn.rb
@@ -2,6 +2,7 @@
 
 print "请输入数字 N，然后按 Enter: "
 n = gets
+m = n.to_i
 
 # while ( ... )
 #   while ( ...)
@@ -9,3 +10,13 @@
 #   end
 # end
 
+
+i = 0
+while (i<=m)
+   j = 0
+   while (j<=m)
+     print i,"x",j, "=",i*j,"\n"
+      j += 1
+   end
+   i += 1
+ end
diff --git a/14-prime.rb b/14-prime.rb
index 8cf1692..b3148dd 100644
--- a/14-prime.rb
+++ b/14-prime.rb
@@ -2,6 +2,28 @@
 
 def is_prime(n)
 # ....
+res = [1]
+  res<<n
+
+  if n == 0 || n == 1
+    return false
+  end
+
+  for i in 2..10
+    if n == i
+      next
+    end
+
+    if n % i == 0
+      res<<i
+    end
+  end
+
+  if res.length > 2
+    return false
+  else
+    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..2106675 100644
--- a/15-guess-number.rb
+++ b/15-guess-number.rb
@@ -9,9 +9,20 @@
   #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
+  if n.to_i < target
+    puts "太低了，再猜一次! "
+    print "请猜一个 n~99的数字N，然后按Enter: "
   end
 
-end
\ No newline at end of file
+
+  if n.to_i > target
+    puts "太高了，再猜一次"
+    print "请猜一个target~99的数字N，然后按Enter: "
+  end
+
+if n.to_i == target
+  puts "恭喜猜中啦! "
+break
+end
+
+end
diff --git a/16-array-sum.rb b/16-array-sum.rb
index 9b4910b..5af3f7a 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)
-  #....
+   max = array.sort.last
 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..29766a0 100644
--- a/17-array-stats.rb
+++ b/17-array-stats.rb
@@ -14,7 +14,20 @@
 
 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
+ i = arr.length
+ arr.each do |i|
+   sum += i
+ end
+
+ ave = sum/i
+
+ max = arr.sort.last
+ min = arr.sort.first
+
+
+
+ puts "总和是 #{sum}"
+ puts "平均是 #{ave}"
+ puts "最大值是 #{max}"
+ puts "最小值是 #{min}"
diff --git a/18-square.rb b/18-square.rb
index 226e1c1..6f2c3ac 100644
--- a/18-square.rb
+++ b/18-square.rb
@@ -7,4 +7,10 @@
 
 # ...
 
-puts arr.to_s
\ No newline at end of file
+for i in 0..(n.to_i)-1
+   arr<< i**2
+ end
+
+
+
+ puts arr.to_s
diff --git a/19-filter.rb b/19-filter.rb
index ef7e515..44ce470 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)
-  #...
+    result = []
+   arr.each do |i|
+     if i % 2 == 0
+       result.push(i)
+     end
+   end
+
+   return result
 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..a64b641 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)
-  #...
+    result = []
+     arr.each do |i|
+       if i % 2 == 0
+         result.push(i)
+       end
+     end
+
+     return  result.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).to_s" # 应该是 [42, 46, 68, 86]
diff --git a/21-selection-sort.rb b/21-selection-sort.rb
index e5e7eae..2dbbe9b 100644
--- a/21-selection-sort.rb
+++ b/21-selection-sort.rb
@@ -2,11 +2,26 @@
 # https://zh.wikipedia.org/wiki/选择排序
 
 def selection_sort(arr)
-  #...
+    len = arr.length - 1
+
+   for i in 0..len
+     min = i
+     for j in i1..len
+       if arr[j]< arr[min]
+         min = j
+
+         temp = arr[min]
+         arr[min] = arr[i]
+         arr[i] = temp
+       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..4f5f76b 100644
--- a/22-missing.rb
+++ b/22-missing.rb
@@ -5,5 +5,7 @@ def find_missing(arr)
 end
 
 answer = find_missing( [2,2,1,5,8,4] )
+arr1 = [0,1,2,3,4,5,6,7,8,9]
+arr2 = arr1 - arr
 
 puts answer.to_s # 应该是 [0,3,6,7,9]
diff --git a/23-hash-max.rb b/23-hash-max.rb
index 6fb227e..ffddd51 100644
--- a/23-hash-max.rb
+++ b/23-hash-max.rb
@@ -1,7 +1,9 @@
 # 给定一 Hash，输出有最大 value 的 key
 
 def find_max(hash)
-  # ...
+    arr = hash.values
+   max = arr.sort.last
+   return hash.key(max)
 end
 
 h = {
@@ -15,5 +17,3 @@ 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..5af0c84 100644
--- a/24-hash-even.rb
+++ b/24-hash-even.rb
@@ -2,7 +2,21 @@
 
 def find_even_keys(hash)
 
-  # ... (请回传一个数组)
+    value = hash.values
+     a = []
+     for i in value
+       if i%2 == 0
+         a<<i
+       end
+     end
+
+     b = []
+     for j in a
+       c = hash.key(j)
+       b<<c
+     end
+
+     return b
 
 end
 
@@ -17,5 +31,3 @@ 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..2b4e6bc 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..55b0724 100644
--- a/26-hash-filter.rb
+++ b/26-hash-filter.rb
@@ -10,7 +10,18 @@
 
 # ....
 
-puts "所有成年人，并由小到大: _________"
+a = []
+ for i in arr              #这里i就是arr中的值，也就是一个个hash.
+    if i["age"] >= 18
+      a<<i
+    end
+ end
+
+
+ result = []
+ result = a.sort_by{ |i| i["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..5c014d9 100644
--- a/27-class.rb
+++ b/27-class.rb
@@ -1,5 +1,9 @@
 class Person
-  # ...
+    attr_accessor :first_name, :last_name
+   def greet
+     puts "Hi, #{first_name} #{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..6bf6afa 100644
--- a/28-word-count.rb
+++ b/28-word-count.rb
@@ -2,4 +2,12 @@
 
 doc = File.read("wordcount.txt")
 
-# ...
+count = Hash.new(0)
+ doc.each_line do |line|
+   words = line.split
+   words.each do |word|
+     count[word] = 1
+   end
+ end
+
+ puts count
diff --git a/29-todos.rb b/29-todos.rb
index 0bddde2..f326737 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)
+        target.write("\n")
+       end
+     target.close()
     break;
   else
     puts "看不懂，请再输入一次"
   end
 end
-