液压控制阀按途径不同，可分为（）、（）和（）三大类，分别调节、控制液压系统中液流的（

A．液态氟化氢中存在氢键，所以其分子比氯化氢更稳定

B．阴离子的核外电子排布一定与上一周期稀有气体原子核外排布相同

C．甲烷、白磷的分子都是正四面体结构，因此它们分子中化学键之间的夹角相同

D．若ⅡA某元素的原子序数为m，则同周期ⅢA元素的原子序数有可能为m+11

We don't keep winning games ________ we keep playing well.[ ]

A．because  

B．unless

C．when  

D．while

在团体辅导中，由特点相似的个体组成的团体称为（）。

A．(A) I think now it is the best time to do business in China, though we have had a 50-year relationship.

B．(B) I believe that we could have done more business with China over the past 50 years.

C．(C) Although our company has a history of over 50 years, we are unable to start our business in China.

D．(D) Despite our good relationship over the past 50 years, we need to find a better time for investment here.

车身某个部件拉伸后造成过度拉伸，其原因是什么（）

A、部件变形后强度不够造成的

B、拉伸力过大

C、拉伸程序颠倒或没有及时测量