利乐线与康美线相同点是()
A.8台车
B.全是纸箱车
C.9台车
D.运行线路相同
参考答案:C
You may imagine what great difficulty I had _____ complicated ideas in simple English.[ ]
A. expressing
B. to express
C. expressed
D. express
泵进口压力骤降而使运行泵产生()。