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下列程序的功能是在text1中输入的自然数,分解为3个互不相同的质数(三个质数的和等于输入的自然数),并把分解产生的质数按升序顺序显示在左边的列表框中。例如,输入20,那么在列表框中会显示如下图所示结果。其中,上述界面中“分解”按钮的名称是“Command1”,程序中函数f(x)的功能是判断x是否为质数,如果是质数则返回值为true,否则返回false.

请在下列程序代码的基础上按照要求设计该程序, 完善程序中的划线部分。
Dim n As Integer, a1 As Integer, a2 As Integer, a3 As Integer
Function f(x) As Boolean
f = True
For i =" 2" To Sqr(x)
If x Mod i =" 0" Then _____( 1 )_____
Next i
End Function
Private Sub Command1_Click()
n = _______( 2 )_______
For a1 =" 2" To n
For a2 =" a1" To n
For a3 =" a2" To n
If _______( 3 )_______ And f(a1) And f(a2) And f(a3) Then
List1.AddItem (Str(a1) + " " + Str(a2) + " " + Str(a3))
End If
Next a3
Next a2
Next a1
End Sub
(1)
(2)
(3)
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同类题3

小李编写一个统计学生选考科目的 VB 程序,算法的基本思想是:检查每位学生选课组合的编码是否有效,对有效选择结果进行科目统计,根据各科占有效人数的百分率求出各科排名。程序运行时,单击“显示”按钮 Command1,学生选课数据显示在列表框 List1 中,各科编号及对应科目名称显示在列表框 List2 中,单击“统计”按钮 Command2,选课结果按各科百分率由高到低显示在列表框 List3 中,程序运行结果如图所示。

现上述功能的 VB 程序如下,请回答下列问题:
(1)学生选课的编码数据存储在数据表中,其字段名为__________________。
(2)请在划线处填入合适的代码。
Dim ach(1 To 500) As String  '存储各学生选课编码
Dim bno(1 To 10) As Integer '存储各科目编号
Dim bname(1 To 10) As String '存储各科目名称
Dim bnum(1 To 10) As Integer  '存储各科目被选次数
Dim bmc(1 To 10) As Integer '存储各科目被选的名次
Dim n As Integer, num As Integer
Private Sub Command1_Click()
Dim i As Integer, km As String
km = "物理化学生物政治历史地理技术"
Dim cn As New ADODB. Connection, rs As New
ADODB. Recordset, sql As String
cn. Open "provider=Microsoft. Jet. oledb. 4. 0;Data Source =" + App. Path + " \students. mdb"
rs. Open "select ∗ from choose", cn
Do While Not rs. EOF
n = n + 1 : ach(n) = rs. Fields("subject") : rs. MoveNext
Loop
rs. Close: cn. Close
Set rs = Nothing
Set cn = Nothing
For i = 1 To 7
bno(i) = i: bname(i) = Mid(km, (i - 1) ∗2 + 1, 2)
List2. AddItem Str (bno (i)) + " - - -" +bname(i)
Next i
End Sub
Private Sub Command2_Click()
Dim i As Integer, j As Integer, k As Integer
Dim c As String, per As Integer
For i = 1 To n
If check(ach(i)) =True Then
For j = 1 To 3
c = Mid(ach(i), j, 1)
bnum(Val(c)) = _________
Next j
num = num + 1
End If
Next i
i = 1
Do While i <= 7  '该循环得到各学科被选人数的名次
bmc(i) = 1
For j = 1 To 7
If bnum(j) > bnum(i) Then __________
Next j
i = i + 1
Loop
For i = 1 To 7
For j = 1 To 7
If _________Then
per = Int(bnum(j) ∗ 100 / num ∗ 100)/ 100
List3. AddItem Str(bno(j)) + "---" +bname(j) + "---" + Str(per) + "%"
End If
Next j
Next i
End Sub
Function check(s As String) As Boolean
'代码略,若学生选科代码有效,函数返回 True,否则返回 False
End Function