(填入适当的介词)Bob spent two hours ______ doing his homework yesterday evening．

根据句意，填入适当的介词

Bob spent two hours ________ doing his homework yesterday evening.

Americans thinks travel is good for people. Some even think it can help one of the country’s

w   1.    problems---crime.

Crime w  2.    a lot of people. Every year, the n   3.    of crimes goes up and up. They often come from sad homes, with only one parent or no parents at all. There are problems with drugs.

There are many young criminals in prison. But prison doesn’t change them---60 to 70 percent will go b  4.   to crime when they come out of prison.

One man, Bob Burton, t  5.   of a new idea. In the old days, young men had to live a hard life on the road. They learned to be strong and b  6.  , and to help their friends in time of danger. This helped them grow into men. So Bob started “Vision Quest(幻想探究)”.

He takes young criminals on a long, long j  7.   with horses and wagons(马车) 3,000 miles through 7 states. They are on the road for more than one year. The young people on Vision Quest all have bad problems.  Most of them have already spent time in prison.  This is their last c     8.  .

It’s hard work on the work. The day starts before the sun comes up. The boys and girls have to feed the horses. Some of them have never loved anyone before, b  9.   they can love their horses. That love can help them to start a new life.

Not all young people in Vision Quest will leave crime behind them. 30 or 40 percent will one day be in prison a  10.  . But that’s a lot better than 60 or 70 percent. Bob is right. Travel can be good for them.

Paula: Hi Bob. You look (1)          !

Bob: I don’t feel great, Paula.

Paula: Is there something (2)          ？Have you been to the doctor’s?

Bob：No, I’m not ill. I’m just a bit tired. I’m probably not sleeping enough.

Paula: You shouldn’t go out so late then.

Bob：I’m not going out at all actually. I’m too busy (3)          . I (4)          

last night.

Paula: Staying up? But the exams are two months away.

Bob：I know, but I’ve got a lot to do. I didn’t do much last term. I wish I’d been more like you!

Paula: Well, yeah, I went to every class and I took lots of (5)          . After class I spent time looking through all the key (6)          I made during class.

Bob：Have you started preparing for the exams yet?

Paula: Not yet. I’ll probably start next week, but I’m not going to stay up all night doing it! If you don’t sleep enough, you can’t (7)         and you don’t learn anything. Anyway you should have a weekend off.

Bob：I don’t think so. I can’t (8)         the time.

Paula: Of course you can! Why don’t you go to do some (9)         work with me? You used to be a (10)         of our Helping Team.

Bob：I know, I do need some time to relax.