Scientists ______ SARS for several months before a major discovery was made in the field.
| A．had been studying | B．have been studying |
| C．have studied | D．are studying |
The paper is due next month, and I am working seven days ______ week, often long into______night.
| A．a; the | B．the;不填 | C．a; a | D．不填；the |
---I am going to Spain fort a holiday soon.
--- ______.
| A．It’s my pleasure | B．Never mind | C．Leave it alone | D．Good for you |
the morning train, he would not have been late for the meeting.
| A． | Did he catch | B． | should be catch | C． | has he caught | D． | Had he caught |
I think _______ impresses me about his painting is the colours he uses.
| A．what | B．that | C．which | D．who |
The two countries are going to meet to _______ some barriers to trade between them.
| A．make up | B．use up | C．turn down | D．break down |