useful adj. 1.有用的,有益的,有效的,有帮助的。 2.〔俚语〕值得称赞的,精通…的 (at)。 make oneself generally useful 事事有用,事事帮得来忙 (He must make himself generally useful. 他可事事都干得来)。 a pretty useful performance 相当精采的演出。 His wife is very useful at cooking. 他的妻子很会做菜。 adv. -ly ,-ness n.
Streaming from the hot end to the cold end of the regenerator was found which would waste much useful heating energy . modified structure of the jet pump could control this sort of streaming efficiently 实验中还观察到了直流现象,气体从回热器热端向冷端运动,造成大量的能量浪费,通过改进喷射泵结构可以有效抑制直流。