The Peppered Moth, a kind of insect(昆虫), is found in England. It is light brown in colour and likes to settle(栖息) on trees which are also light brown. This makes the moth difficult to be seen and birds are less likely to notice and eat it.
But with the development of industry(工业) , smoke from factories began to reach the trees where the moth settled. It made the trees blacker. Then something very strange took place: in industrial areas, the Peppered Moth began to change colour. It became darker as well. Though the change took several years, some scientists soon notice that newly-born moths were a little darker than usual.
A scientist with the name Kettlewell decided to make a careful study of this phenomenon(现象). He marked some of the light moths and some of the darker ones, and set them free in the woods near Bermingham, an industrial city. Later, he recaptured(重新捕获) as many as the marked moths as possible. The results were as follows.
| light moths
| darker moths
|
Moths set free
| 201
| 601
|
moths recaptured
| 34(16%)
| 206(34%)
|
Kettlewell's research (研究) was done in the early 1950s. Soon afterwards Britain introduced new laws to reduce smoke and factory pollution.
Can you imagine what would happen to the Peppered Moth as the air became cleaner again?
小题1:The Peppered Moth began to change its colour in industrial areas because
.
| A．it itself liked to |
| B．it could be like the colour of its living-place |
| C．it had to keep the balance of nature |
| D．it was usually dark brown |
小题2:From the results of Kettlewell's research, we can see that
.
| A．many more of the light moths were killed or eaten |
| B．more than one-fifth of the light moths was not killed |
| C．three times as many dark moths were kept safe as light ones |
| D．more dark moths were killed in industrial areas |
小题3:As the air became cleaner,
.
| A．the number of the light moths became larger |
| B．the total number of the light moths remained unchanged |
| C．there were more of the darker moths and fewer of the light ones |
| D．the darker moths changed into the light ones suddenly |