Every possible means _____ to prevent the pollution,but the sky i_英语解答

Every possible means _____ to prevent the pollution,but the sky is still not clear.
A is used B are used C has been used D have been used

人气：121 ℃　时间：2020-03-27 08:35:50

解答

答案为C首先我们看到means（方法）这个词,它是单数和复数的形式一致的.再看Every possible means,每个可能的方法,那当然是单数了.排斥BDC已经被使用了,现在完成时态与后面的but结果相对应,即先后关系.A被使用了.没有...