—They are quiet，aren't they?
—Yes.They are accustomed ________ at meals.
A．to talk B．to not talk
C．to talking D．to not talking
________ the meeting himself gave them a great deal of encouragement.
A．The president will attend
B．The president to attend
C．The president attended
D．The president's attending
The flu is believed ________ by viruses that like to reproduce in the cell inside the human nose and throat.
A．causing B．being caused
C．to be caused D．to have caused
—Is Bob still performing?
—I'm afraid not.He is said ________ the stage already as he has become an official.
A．to have left B．to leave
C．to have been left D．to be left
I like getting up very early in summer.The morning air is so good ________.
A．to be breathed B．to breathe
C．breathing D．being breathed
It is said in Australia there is more land than the government knows ________.
A．it what to do with B．what to do it with
C．what to do with it D．to do what with it
