New technology ______ to make sure that the cars, taxis, buses and trains we use

题型：不详难度：来源：

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

答案

C

解析

本题主要考查动词的时态及语态的应用。第 1 空强调目前所正在进行的一种行为。由于主语是动作的承受者，应该使用现在进行时的被动语态；第 2 空强调一般经常性的行为，应该用一般现在时。因此本题的正确答案选C。