题目内容
2020年军队职称英语-卫生类B级词汇指导重难点词组(7)
提问人:韩莉发布时间:2019-12-20
New technology ______ to make sure that the cars, taxis, buses and trains we use ______ the air.
A.is used; not to pollute
B.has used; is not polluted
C.is being used; do not pollute
D.has been used; to pollute
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