主动提出的

She definitely had an ulterior motive in offering to help.

她出帮忙, 肯定有不可告人的机。

When this method is applied to the spiral bevel gears of an airplane engine, the results show that it is more reasonable than TCA and the precontrol method.

出了一种在初始设计阶段就可保证弧齿锥齿轮具有预期加载接触性的设计方法，并将其用于某航空发机中央传弧齿锥齿轮的齿面综合。