useful adj. 1.有用的,有益的,有效的,有幫助的。 2.〔俚語〕值得稱贊的,精通…的 (at)。 make oneself generally useful 事事有用,事事幫得來忙 (He must make himself generally useful. 他可事事都干得來)。 a pretty useful performance 相當(dāng)精采的演出。 His wife is very useful at cooking. 他的妻子很會做菜。 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 實(shí)驗(yàn)中還觀察到了直流現(xiàn)象,氣體從回?zé)崞鳠岫讼蚶涠诉\(yùn)動,造成大量的能量浪費(fèi),通過改進(jìn)噴射泵結(jié)構(gòu)可以有效抑制直流。