威特单体泵的润滑方式为()
A.飞溅润滑
B.自然润滑
C.强制润滑
D.柴油润滑
参考答案:C
You really need to go out and get some fresh air and sunshine. You _______ overworked during the last
fortnight.[ ]
A. have been
B. were
C. had been
D. would be
下显示的是19世纪英国人口结构的变化状况,其中曲线①代表的阶级成份是
A.地主
B.资本家
C.工人
D.农民