1. have/get one's hands full 很忙，应接不暇
Three emergency cases came into the hospital at the same time and the doctors really had their hands full.
2. be up to one's neck 忙得不可开交
I can't possibly come out tonight, I'm up to my neck in work.
3. a million things 很多很多事情
It's hard to slow down when you are trying to do a million things.
4. be as busy as a bee 忙忙碌碌，忙死忙活的
He was as busy as a bee trying to put the house in order.
5. busy as a beaver 忙得团团转
He is working so hard that he is as busy as a beaver.
6. be tied up 被占用，很忙
I'll be tied up the rest of the week, I am afraid.
7. in the middle of something 正忙于某事
I'm in the middle of something. Could you call back later?
8. time to catch one's breath 喘口气的功夫
I don't even have time to catch my breath.