这是一个用来形容一大早就起来的idiom.
For examples:
We were up at the crack of dawn to watch the sun rise.
我们一大早起来去看了日出。
It's a long drive, so we sef off at the crack of dawn.
路程比较远，所以我们一大早就出发了。
Paul got up at the crack of dawn everyday to hike around the island.
保罗每天都早起环岛徒步旅行。
这个idiom 和上面那个有点类似，只是时间上要比它稍微晚一些。
For examples:
We have to get up bright and early to catch the train to Paris.
我们得早点起来去赶到巴黎的火车。
Since there's no needs to be hurry, so we won't get up bright and early tomorrow.
因为不需要赶时间，所以我们明天不会那么早起。
该idiom指的是第一件要做的事。
For examples:
We need to check out first thing.
我们明天第一件要做的就是退房。
You need to call and make a reservation first thing. We don't want to miss out.
你得先打电话预约。我们可不想错过。
当你准备结束一天或晚上的工作时，可以用这两个idiom. 它们的意思是:打算收工，或到此为止。
For examples :
We were so exhausted that we decided to call it a day, and ordered room service in our hotel room.
我们实在是精疲力尽了，所以决定收工，然后在酒店的房间里叫了客房服务。
Let's just call it a day and go to the pub!
我们今天就到此为止，去酒吧吧！
I need to call it a night, I've been dancing for 12 hours.
我已经连续工作了12个小时，现在得收工了。
这是一个用来形容你按耐不住，想要出去玩，或没办法在一个地方呆太久的idiom.
For examples:
My friends always tell me that I have got itchy feet.
我朋友常说我总是想出去玩。
After being away from work for so long, it's really difficult to sit at my desk for eight hours.
在离开工作岗位这么久之后，持续坐在桌前八个小时实在是难熬。
I noticed that Ben is really distracted at the moment. Do you think he's got itchy feet?
我注意到本现在很是心烦意乱，你觉得他是不是有点按耐不住了？