play by ear meaning in English

看情况决定
凭听觉记忆演奏, 没有充分准备地处理某事
随机应变，视情形而定
听记演奏
走着瞧

He had no time to prepare for the party , so he had to play by ear
他没有时间为这次聚会做准备，只好随机应变了。
He had no time to prepare for the party , so he had to play by ear
他没有时间为这次聚会做准备，只好凭记忆演奏了。
He had no time to prepare for the party . so he had to play by ear
他没有时间表为这次聚会做准备.只好凭记忆演奏了
B : i don ' t know . i think we should just play by ear and have a good time out today
不知道。我想我们应该(出来了)就好好的玩,看情形再说?