New technology ______ to make sure that the cars, taxis, buses and trains we use ______ the air.
A．is used; not to polluteB．has used; is not polluted
C．is being used; do not polluteD．has been used; to pollute
C

本題主要考查動(dòng)詞的時(shí)態(tài)及語態(tài)的應(yīng)用。第 1 空強(qiáng)調(diào)目前所正在進(jìn)行的一種行為。由于主語是動(dòng)作的承受者，應(yīng)該使用現(xiàn)在進(jìn)行時(shí)的被動(dòng)語態(tài)；第 2 空強(qiáng)調(diào)一般經(jīng)常性的行為，應(yīng)該用一般現(xiàn)在時(shí)。因此本題的正確答案選C。
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