that would be less detrimental to the war effort. 能不能挑个不影响战果的法子
Exhausted by the effort of travelling such a distance on land, 在陆地上的长途跋涉使它筋疲力尽
so that, with very little effort, the birds can soar over the city. 游隼不费吹灰之力便可以在城市上空翱翔
and the rewards for the effort can be disappointing. 努力捕食却往往空手而归
and they can soar for weeks on end with minimal effort. 它们只需要很小的付出就能在海上飞行好几个星期