There ____________ an English book in my schoolbag. [ ]
A. are
B. aren't
C. is
答案:C
His sister's never been to the Summer Palace, _____? [ ]
A. is she
B. has she
C. hasn't she
D. isn't he
在日常工作中,防爆工具连续敲击()次后应该对工具的表面附着物进行处理,揩净后再做使用,千万不要连续使用。
A、15
B、20
C、25
D、30