“书山有路勤为径，学海无涯苦作舟”这句话说明学习中到处是苦，没有快乐。 [ ]
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—How often does Mike go to his driving lesson?
—_____. [ ]
A. Once
B. Two times a week.
C. For two hours
D. Once a week
在煤巷掘进工作面和采煤工作面对无突出危险区进行医域验证时，工作面每推进10~50m至少进行（）次区域验证。
A.1
B.2
C.3
