（）可能是造成槽车装车臂冷态下旋转接头卡涩的原因。
A、滚珠磨损
B、导槽磨损
C、接头密封磨损
D、氮气压力过高
参考答案：C
直角两边延长，角就变大了。[ ]
From the look on his husband's face, she knew that he did it ____ to make her happy. [ ]
A. right away
B. as a matter of fact
C. in the end
D. on purpose
