C. Man is to take measures to control the growth of deserts.

　　D. Deserts have grown at a fast speed in the past 10 years.

　　 Comera is the only place in the world which has a whistle (口哨) language. We do not know how and why it began. But we can imagine the reasons for the beginning of the whistle language. There are many deep valleys (峡谷) on the island. A person on one side of a valley cannot easily shout to a person on the other side. But he can whistle and be heard four miles away and the record is seven miles. The people who live on the island usually have good teeth, and this helps them to whistle well. They must also have good ears so that they can hear other whistlers.

　　We can understand why the whistle language continues. It is very useful on the island, and quite easy to learn. When somebody is hurt or ill, the whistle language takes the place of telephone. If the sick person is quite far away from the town, people pass the message from one to another. A boy guarding cattle (放牛) on a hillside whistles to a man fishing from his boat. The last one is able to describe the trouble fully and exactly to the doctor in town. People help one another in the same way when a car breaks or a cow is lost.

　　The whistle language is hundreds of years old, and probably it will continue to live on for hundreds of years more. Radio and TV often kill the special ways of speaking in the different parts of a country. But on Comera you are nobody if you cannot whistle. Perhaps soon after TV arrives on the island, the people there will be whistling the news and other facts and opinions.

28. If a person on Comera island is ill, ____.

A. others will phone the doctors in town

B. people will take him to town by carriage

C. his family will take him to the hospital

D. the whistle language will help pass the message to the doctor

29. From this passage we know radio and TV ____ at that time.

A. killed the special way of speaking B. whistled all the news and opinions

C. did not appear on Comera island yet D. helped Comera people to communicate

30. Comera island is special because____ .

A. many visitors go there every year