He painted his bedroom black. It looks dark and dreary. He should choose a different color（）.

单项选择题I locked myself out of my apartment. I didn't know what to do. You may call your roommate（）.

A．could have called
B．might have called
C．would have called
D．must have called

单项选择题He didn't to return earlier than 3 o'clock（）.

A．was not expected
B．did not expect
C．was expected not
D．was not expecting