A four-character password consists of one letter of the alphabet and three different digits between 0 and 9, inclusive. The letter must appear as the second or third character of the password. How many different passwords are possible

A．5,040

B．18,720

C．26,000

D．37,440

E．(E) 52,000

设有如下通用过程：Public Sub Fun(a( )，ByVal x As Integer) For i=1 To 5 x=x+a(i) NextEnd Sub 在窗体上画一个名称为Text1的文本框和一个名称为Command1的命令按钮，然后编写如下的事件过程：Private Sub Command1_Click( ) Dimsn(5)As Variant For i=1 To 5arc(i)=i Next n=10Call Fun(arr( )，n) Textl.Text=n End Sub 程序运行后，单击命令按钮，则在文本框中显示的内容是

A．10

B．15

C．25

D．24