between a rock and a hard place，字面意思“在石头与硬的地方中间”，真实含义是左右为难，进退维谷，陷入困境。

【例句】
I hate my job but cannot quit owing to my economic condition. I'm stuck between a rock and a hard place.
我讨厌我的工作，但由于我的经济状况，我不能辞职。我进退两难。

I can't make up my mind whose side I am on; I'm caught between a rock and a hard place.
我无法决定我站在谁的一边，我左右为难。