Private Sub Command1_Click()

    Text1.Text = ""

    Text2.Text = ""

    Text3.Text = ""

    Text4.Text = ""

End Sub

Private Sub Command2_Click()

    Dim a As Single, b As Single, c As Single

    Dim x1 As Single, x2 As Single, det As Single

    a = Val(Text1.Text)

    b = Val(Text2.Text)

    c = Val(Text3.Text)

    det ={#blank#}1{#/blank#}      ‘（根的判别式b²-4ac）

    Select Case det

    Case Is > 0

        x1 = (-b + Sqr(det)) / (2 * a)

        x2 = (-b - Sqr(det)) / (2 * a)

        Text4.Text = "方程有两个实数根" & " x=" & Str(x1) & "   x=" & Str(x2)

    Case Is = 0

        Text4.Text = "方程有两个相等的实数根 x=" & Str(x1)

    Case {#blank#}2{#/blank#}

        Text4.Text = "此方程无实数根"

    {#blank#}3{#/blank#}

End Sub

Private Sub Command1_Click( )

    Dim a As Integer, b As Integer

    a = val(“9”)

    b = sqr(a)

    Texr1.Text =str (b)

End Sub

import math

for num in range(100,1000):
    

    if num==pow(gw,3)+pow(sw,3)+pow(bw,3):      #pow(x,y)函数返回xy的值

        print(num）

上述程序段中加框处应该填入的代码段是（  ）

str1 = “key”

Str2 = “board”

Print(str1+str2)