1. off-guard 措手不及的;没有提防的；无思想准备的
英文释义：If someone is caught off-guard, they are not expecting a surprise or danger that suddenly occurs.
The question caught her completely off-guard.
2. at sea
The absent-minded boy is always losing his books. I am all at sea in the adolescent stage of my life.
3. off-balance 冷不防的；大出意料的；极为慌乱的
英文释义：If someone is caught off-balance, they are extremely surprised or upset by a particular event or piece of news they are not expecting.
Mullins knocked me off-balance with his abrupt change of subject.
4. in the dark
I'm as much in the dark as you.
英文释义：If you are overwhelmed by a feeling or event, it affects you very strongly, and you do not know how to deal with it.
I was overwhelmed by the sheer quantity of information available.