采掘工作面发生冒顶事故时会出现（）预兆。
A、响声
B、温度升高
C、掉渣
D、煤壁片帮
参考答案：A, C, D
先选中表格中的所有行，然后按Delete键不能删除整个表格。( )
____, Franks never seems able to do the work satisfactorily. [ ]
A. As hard he tries
B. Try hard as he might
C. As hard as he tries.
D. Try, as hard as he might
