The man we followed suddenly stopped and looked as if          whether he was going in the right direction.

A．seeing

B．having seen　

C．to see

D．to have seen

窗体上有三个按钮Command1、Command2和Command3，如以下代码所示，该程序的功能是______。Private Sub Command1_ Click() Command2. Enabled=False Command3. Visible =FalseEnd Sub

A．当单击按钮Command1时，按钮2和按钮3都不可用

B．当单击按钮Command1时，按钮2和按钮3都不可见

C．当单击按钮Command1时，按钮2不可用和按钮3不可见

D．当单击按钮Command1时，按钮2不可见和按钮3不可用