Question

9. Every possible means to prevent the air pol- lution,but the sky is still not clear.

   A. is used        B. are used

   C. has been used   D. have been used

Answer 1

9. C

9. C解析：句意：為了防止空氣污染，每 種可能的辦法都試過了，但是天空還是不晴朗。means意為“辦法，方法”，單復(fù) 數(shù)同形，因?yàn)榇颂幱衑very修飾，故應(yīng)看 作單數(shù);由句意可知，此處應(yīng)用現(xiàn)在完成 時(shí)的被動(dòng)語(yǔ)態(tài)，故選C項(xiàng)。