第22题: [单项选择]关于齿轮的下列说法中,不正确的是() A. 对齿轮传动提出的两项基本要求是:传动要平稳,承载能力强 B. 惰轮可改变传动方向,但不改变传动比 C. 圆锥齿轮传动用于传递两相交轴之间的运动和动力,通常两相交轴交角为45 D. 对于闭式传动,一般常用浸油润滑和喷油润滑 参考答案:C
第31题: [单项选择]{{B}}Questions 11 to 18 are based on the conversation you have just heard.{{/B}} A. Sending the next package earlier. B. Waiting patiently. C. Using air freight. D. Looking for the package. 参考答案:C 答案解析:[听力原文]
M: I sent the package over 10 days ago and it still hasn’t arrived.
W: Maybe you should sen