Are they working? —No, they are talking ______ the phone.[ ]

I am interested in that beautiful bag. What do you charge for it? — $ — ______ , but I can’t afford it.

The printer is used ______ printing information. [ ]

Alice is one of the students who I am sure always best in most difficult situations.

_______ for your step, Jim, or you might fall into the lake. – Well, I got it．