6. Language learning is cumulative： you cannot put it off until the weekend. Study one or two hours for every class hour if you want a good mark.(   )

5. The only wonder is that so many states insist on closing their ears to the message. Tobacco taxes improve public health. They raise money and most particularly,they deter people from taking up the habit as teens,which is when nearly all smokers are addicted. Yet the rate of taxation varies widely.(   )

4. In fact,only about 80 ocelots,an endangered wild cat,exist in the US today.(   )

3. I feel that since you are my superior (上司) ，it would be presumptuous of me to tell you what to do.(   )

2. Pruning is important because it encourages the growth of tender shoots,or young leaves.(   )

1. Krabacber suffers from SAD. which is short for seasonal affective disorder,a syndrome characterized by severe seasonal mood swings.(   )

5. He always stays        to write articles        a magazine.

4. They worked in different cities,but they often kept      touch      each other.

3.      a result of the dam,the water level of the lake was going to rise         63 metres.

2. The dam was built      several reasons which I didn’t know much     .