问题
选择题
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
答案
答案：C
搜题请搜索小程序“爱下问搜题”
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
答案：C