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
B:are used
C:has been used
D:have been used
正确答案是：
同类题型
But for the help of my English teacher, I ____ the first prize in the English Writing Competition.
When I passed the entranceexamination, my family_____ me ______ my success.
People have planted a great many trees in order to ________ wind and sand in the desert. [ ]
They stayed with me three weeks, _____ they drank all the wine I had.