操作室一般不准有明火作业，确因生产需要，需领取（）后方可作业。
A.停电牌
B.操作牌
C.动火证
参考答案：C
The teachers are doing what they _____ their students. [ ]
A. can to teach
B. can teach
C. can teaching
D. can to teaching
3G终端宣传的重点是智能。（）
