题目内容
The scientists are ________ a research ________ the cause of heart diseases.
- A.carried out; on
- B.carrying out; into
- C.performing; in
- D.performed; of
B
导解:这里的习惯搭配为perform/carry out a research on/ into sth.
导解:这里的习惯搭配为perform/carry out a research on/ into sth.
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