进入煤气设施内作业时,应当对煤气设施内的气体进行检测,且检测时间不能早于作业开始前()min。
A.10
B.30
C.60
参考答案:B
属于胃癌的癌前病变的是()。
A.慢性萎缩性胃炎
B.慢性浅表性胃炎
C.胃息肉
D.胃酸缺乏症
E.胃溃疡
Jim doesn’t like the soap operas at all. He can't ____ them. [ ]
A. love
B. stand
C. understand
D. know