Question

Do you have trouble getting started in the morning? Do you have problems learning early in the day? If you do, you are not alone, _1.__ They learn better at night than they do in the morning.

To investigate when cockroaches(蟑螂) learn best, researchers at Vanderbill University tested the insects for which odor(peppermint 薄荷 or vanilla 香草) they preferred. Most cockroaches preferred the smell of vanilla to that of peppermint at all times. __2.__ Therefore, the scientists trained the cockroaches to prefer the peppermint smell by rewarding the insects with a taste of sugar water when they approached a peppermint smell. _3.__

When the cockroaches were trained at night, they remembered the new associations(peppermint＝sugar water; vanilla＝salt water) for up to 48 hours. However, if the cockroaches were trained in the morning, they quickly forgot which smell went with which water. __4._

So, cockroaches learn better at night than they do in the morning. _5._ Because of this, it is likely that information they gather at night will be more useful to them. These experiments provide some clues about the interactions between body rhythms, learning and memory.

A．When these insects moved toward a vanilla smell, on the other hand, they were punished with a taste of salt.

B．This result thus shows that the time when they were trained decided the effect of their learning.

C．They are often more active and tend to search for food during the night.

D．They were also found to like sugar water, but not salt water.

E．Cockroaches have the same problem!

F．But they prefer warm conditions found within buildings.

G．Pest species adapt easily to their environment.

Answer

1.E

2.D

3.A

4.B

5.C

【解析】科学家通过试验说明了蟑螂更适于夜间行动，在夜间它们身体的各个机能都好于早晨，所以工作效率也会更高。

1.E 前面说到你不再孤单，即还有别人像你一样不喜欢早起、不喜欢早上学习，所以接下来就要说有同样问题的人或物是谁了。故选E项。

2.2】D 根据下文中“with a taste of sugar water...”可知选D项。

3.3】A 本段介绍了蟑螂对糖水和盐水不同反应的试验，前面介绍了糖水，接下来肯定要说到盐水。故选A项。

4.4】B 此处是一个总结句，是对以上试验的一个结论。故选B项。

5.5】C 试验证明了蟑螂在夜间的反应更快，所以效率也会更高。故选C项。