for i in range(10):

    k=int(input())

    if k<=20 and k>0:

        if k>15:

            if k>18:

                x=0

            else:

                x=1

        else:

            if k>12:

                x=4

            else:

                x=5

实现上述功能的程序如下，请在划线处填入合适的代码。

def isprime(x):

    for i in range(2,x):

        if {#blank#}1{#/blank#} :

            return False

    return True

n=int(input("请输入一个正整数 n:"))

c=0

k=3

while k<=n-2:

    if isprime(k) and {#blank#}2{#/blank#} :

        print(k,k+2)

        {#blank#}3{#/blank#}

    k=k+1

print("共有"+str(c)+"对双胞胎数")

小王利用VB程序实现这一加密功能，程序界面和代码如下所示：

Private Sub Com_ jm_ Click()

    Dim x As String, ch As String, cl As String

    Dim s1 As String, s2 As String, s As String

    Dim i As Integer, n As Integer, y As Integer

    x= Text1. Text

    n=Len(x)

    For i=1 To n

        ch= Mid(x, i, 1)

        If ch >= "0" And ch <= "9" Then

               ①     

            s2=s2 & y

        Elself ch >="a" And ch<="z" Then

            y=(Asc(ch)-Asc("a")+3) Mod 26

                 ②   

            s1=c1+s1

        Else

            y=(Asc(ch)- Asc("A")+3) Mod 26

            c2=Chr(Asc("A")+y)

            s1=c2+s1

        End If

    Next i

        ③  

    Text2 Text=s

End sub

s=input("请输入字符串:")

count=0

for i in s:

    if i>="0" and i<="9" :

        count+=1

print(s[count:count+3])

若输入的字符串为"AB12CCC222GGBD",则程序运行的结果为（   ）

s＝0

for i in range（1，6，2）：

    s＝s＋1

print（s）