记住：“去睡觉”不只是"go to bed"

I'm off to bed.

强调上床是要去休息

I finally succeeded in packing her off to bed.

最后我总算是把她打发上床睡觉了。

It's bedtime. 睡觉时间

Put your toys away now, it's bedtime.

把玩具放好，该上床睡觉了。

I'm going to hit the sack.

sack在这里是指床，hit是去床上睡觉的意思。

I've got a busy day tomorrow, so I think I'll hit the sack.

明天我将度过繁忙的一天，因此我得上床去睡觉了。