题目内容：

A sandstorm is a kind of strong wind that blows over the desert. It raises sand and dust into the air and makes it difficult to see the sun and it reduces visibility of most to zero. It is also known as a dust storm. Some storms are usually the result of convection currents（对流气流）caused by the strong heating of the ground. Then wind is usually strong enough to move a small hill of sand. It can make travel very difficult and can even destroy roads in flat dry areas such as those in the United States.

The Simoom is the strong hot wind that comes across the Sahara and Arabian desert. This wind is the reason for much of the dust in the air over Europe. Evidence（证据）of the dust from Simoom wind has also been found at the bottom of the sea at a long distance from the shore.

Alasksi is the strongest sandstorm. It can destroy all the things in his way. It is very dangerous. It has killed more than one hundred people in the area. The Haboob is a sandstorm that often happens in the area of Sudan around Khartoum. Sandstorms, the height as 5,000 ft (1,525m), also happened, although not often in the United States. It is stronger than the Simoom. One that appeared near Tucson, Arizona, on July 16, 1971, was widely proved by meteorologists.（天文学家）。

1.Which of the following is not a name of sandstorm?

A. Simoom

B. Haboob

C. Khartoum

2.The underlined word "visibility" may mean_______ in Chinese.

A. 模糊度

B. 能见度

C. 对流度

3.Which of the following is TRUE according to the passage?

A. Sandstorms carry lots of sand and dust.

B. Sandstorms are also known as rainstorms

C. Sandstorms are usually the result of wind.

4._____shows the right picture of the three sandstorms in the correct way.

 

5.What is the main idea of the passage?

A. When sandstorms happen

B. Where sandstorms happen

C. What sandstorms are