VBA语句 --- 判断语句

Sub 单条件判断()
    If Range("a1") > 0 Then
        Range("b1") = "正数"
    Else
        Range("b1") = "负数或0"
    End If
End Sub

Sub 多条件判断1()
    If Range("a1") >0 Then
        Range("b1") = "正数"
    ElseIf Range("a1") = 0 Then
        Range("b1") = "等于0"
    Else
        Range("b1") = "负数"
    End If
End Sub

Sub 多条件判断2()
    If Range("a1") <>"" And Range("a2") <>"" Then
        Range("a3") = Range("a1") * Range("a2")
    End If
End Sub