Now people like to write articles------computers not--------paper.
| A．on ; on | B．at ; on | C．in ; in | D．with ; with |
The plane was late, _________ we has to wait for half an hour.
| A．because | B．or | C．so | D．but |
Tony never spends money on traveling____ he likes staying at home.
| A．but | B．because | C．though | D．until |
________ is not an easy thing for everyone to master a foreign language.
A. That B. This C. It
The problem must be __________ discovered next time.
A. farther B.far C.further
The doctor was busy _________ on the woman at that time.
A. operating B. operated C. to operate