7. EVERY POSSIBLE MEANS _________ TO PREVENT THE AIR POLLUTION, BUT TH...

7 . - DE THI VA DAP AN TUYEN SINH VAO LOP 10 CHUYEN MONTIENG ANHHA TINHNAM 20122013
Lớp 10 Tiếng Anh DE THI VA DAP AN TUYEN SINH VAO LOP 10 CHUYEN MONTIENG ANHHA TINHNAM 20122013

7

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

A. is used

B. have been used

C. are used

D. has used