31. All his attention______on the computer game, so he even didn't notice his mother enter the room.
We need to get to the root of the problem______ we can solve it.
If you have any doubts about your health, you’d better______ your doctor at once.
Tom had tothe invitation to the party last weekend because he was too busy.
Despite the previous rounds of talks, no agreement______ so far by the two sides.
______ for two days, Steve managed to finish his report on schedule.