New technology to make sure that the cars taxis buses and trains we use the air.A. is

问题补充：

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：

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

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。