串的長度是：
    A)串中不同字符的個數(shù)
    B)串中不同字母的個數(shù)
    C)串中所含字符的個數(shù)且字符個數(shù)大于零
    D)串中所含字符的個數(shù)
    考點分析：串的概念及特點
    VB試題：
    Function FirProc(z As Integer,y As Integer,z As Integer)
     FirProc=2*x+y+3*z
    End Function
    Function SecProc(x As Integer,y As Integer,z As Integer)
     SecProc=FirProc(x,y,z)+x
    End Function
    Private Sub Command1_Click()
     Dim a As Integer,b As Integer,c As Integer
     a=2:b=3:c=4
     Print SecProc(c,b,a)
    End Sub
    A) 21 B) 19 C) 17 D) 34
    考點分析：函數(shù)過程的定義及調(diào)用