车刀复磨时应选择在()
A.正常磨损中期
B.正常磨损结束时
C.急剧磨损后
参考答案:B
They looked _____ each other and kept their secrets _____ themselves.
A.for; to
B.at; for
C.at; to
D.out; at
我国煤炭资源丰富,探明储量居全国前两位的是[ ]
A.山东的辽宁
B.山西和陕西
C.山东和陕西
D.山西和内蒙古