问题

Every possible means ______ to prevent the air pollution, but the sky is still not clear.

A:is used
B:are used
C:has been used
D:have been used

正确答案是：

同类题型

－__________ are you going to learn English－I’m going to practice it again and again.

Our holiday cost a lot of money.— Did it? Well, that doesn’t matter ________ you enjoyed yourselves.[ ]

The flat is too expensive and too big, _____, I’ve grown fond of our little rented flat [ ]

I want to_____ the No. 5 bus to Tian’an Men Square.

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