H₂S浓度为 （）可嗅到臭鸡蛋味，一般对人

A、Sub plus(sum, a , b ): sum = a + b: End Sub

B、Sub plus(ByVal sum , a , b ): sum = a + b: End Sub

C、Sub plus(sum , ByVal a, ByVal b ): sum = a + b: End Sub

D、Sub plus(sum , ByRef a , ByRef b ): sum = a + b: End Sub

在窗体中添加一个名称为Command1的命令按钮，然后编写如下程序： Public x As Integer Private Sub Command1_Click() x=10 Call s1 Call s2 MSgBox x End Sub Private Sub s1() x=x＋20 End Sub Private Sub s2() Dim x As Integer x=X＋20 End Sub 窗体打开运行后，单击命令按钮，则消息框的输出结果为______。

A．10

B．30

C．40

D．50

H2S气体的气味有（）。

A.酸味

B.臭鸡蛋味

C.苦味

D.甜味

下列程序的执行结果为 Private Sub Commandl_Click() Dim s1 As String ,s2 As String s1= "abcd" Call Transfer(sl，s2) Print s2 End Sub Private Sub Transfer (ByVal xstr As String，ystr As String) Dim tempstr As String ystr=tempstr End Sub

A．dcba

B．abdc

C．abcd

D．dabc

Ｈ２Ｓ气体的气味有（）

A.臭鸡蛋味

B.酸味

C.苦味

D.甜味

写出程序运行的结果

Public class Base

Public virtual string Hello() {return “Base”;}

Public class Sub:Base

Public override string Hello() {return “Sub”;}

1. Base b = new Base(); b.Hello;

2. Sub s = new Sub(); s.Hello;

3. Base b = new Sub (); b.Hello;

4. Sub s = new Base(); s.Hello;

H：S气体的气味有()。

A.臭鸡蛋味

B.酸味

C.苦味

D.甜味