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
When I handed the report to John，he said that George was the person ________.
A．to send B．for sending it
C．to send it to D．for sending it to
In my opinion，life in the twenty－first century is much easier than ________.
A．that used to be B．it is used to
C．it was used to D．it used to be
