?随机应变

... out of earshot 不在听力所及范围 play by ear 随机应变，视情形而定 ring a bell 令人想起某件事;听起来耳熟 ...

?视情况而定

... hit the spot (特指吃了食品，喝了饮料之后)精神完整恢复过来或觉得满意;恢复精神;提精神 play by ear 随机应变，视情况而定 fit as a fiddle 身体很健康 ...

?见机行事

... out of this world 非常好 play by ear 见机行事，视情形而定 share a common outlook 有单独的观念 ...