play it cool 不露声色，沉着冷静
chew the cud 好好琢磨
be completely in the dark 一无所知，仍蒙在鼓里
has seen better days 今非昔比
be out of one's depth 力所不及
a drop in the bucket 沧海一粟
play dumb with someone 装聋作哑
be at loose ends 心里没有着落
make both ends meet 收支平衡
turn a blind eye on 装作没看见
keep a straight face 板着脸
be riding for a fall 自讨苦吃
stand on one's feet 自食其力

这个翻译很准确，而且不像自己翻译的那样中国式。译传思翻译价钱很公道，速度也是没得说，解救了我的论文翻译，真是太好了。