I wonder how it ____ that Chinese climbers successfully finished the torch relay on the Mount Qomolangma, where the air is so thin.

Weather changes when the temperature and the amount of water in the atmosphere change. We can see and feel water coming from the atmosphere when we have rain. But the water must somehow get back to the atmosphere. Meteorologists call this the water cycle.

   There are many stages in the water cycle. Rain falls when water vapour in clouds condenses(凝结). Drops of water form and fall to the ground. The water soaks into the ground and feeds streams and rivers. A lot of rain falls into the sea. The heat of the sun evaporates some of the water in the ground and in the rivers, lakes, and the sea. It changes the liquid water into water vapour. The vapour rises onto the air. Water vapour is normally invisible. On a very damp or humid day, however, you can sometimes see water vapour rising from a puddle(水坑) or pond in a mist(薄雾) above the water. Water vapour also gets into the air from living things. Trees and other plants take in water through their roots and give off water vapour from their leaves. People and land animals drink water and breathe out water vapour. In all these ways the water returns to the air. There it gathers to form clouds and condenses to form rain. The rain falls to earth, and the cycle starts again. It continues even if snow or hail(冰雹) fall instead because both eventually melt to form water. The amount of water vapour in the air depends on the temperature. The air is more moist(潮湿) in the tropics(热带) than in the cold polar regions.

1. What is the main idea of the passage?

A. Water cycle.                                 B. Water vapour.

C. How rain forms.                      D. Water, vapour, rain.

2. How many ways of the water returning to the air are discussed in the text?

A. Two.                  B. Three.        C. Four.        D. Five.

3. Whether water vapour can be seen or not depends on _______.

A. how much water is evaporated         B. how good your eyes are

C. in which way water is evaporated           D. climate or weather

4. From the passage we get to know _______.

A. there is more water vapour in the air in the tropics than in cold polar regions

B. there is more water vapour in the air in cold polar region than in the tropics

C. it gets more rain in the tropics than in cold polar regions because there is less vapour

D. the amount of water vapour in the air depends on how often it rains

―Mom, what did your doctor say?

 ―He advised me to live          the air is fresher.

  A. in where             B. in which            C. the place where    D. where

I wonder how it ____ that Chinese climbers successfully finished the torch relay on the Mount Qomolangma, where the air is so thin.

请认真阅读下列短文，并根据所读内容在文章表格中的空格里填入一个最恰当的单词。注意：每个空格只填一个单词。请将答案写在答题卡上相应的横线上。

Each year there is an increasing number of cars as millions of new cars are produced in America . Americans will not live without cars ! However , some have realised the serious problem of air pollution by cars . It is necessary to find ways to solve the problem of air pollution .

One way to clean the air is to build a new kind of clean car . That’s what several of the large car factories are trying to do . But to build a clean car is easier said than done . Progress in this field has been slow .

Another way is to take the place of the car engine by something else . Engineers are now working on it . Many makers believe that it will take years to develop a practical model that can please man .

To prevebt the world being polluted by cars , They have to cut down on the number of their cars and are encouraged to travel and go to work by bike . But this change doesn’t close down ---- many workers may find themselves without jobs if a car factory closes down . And the problem of their pollution would become less important than that of unemployment.

Title : (1) _____ and Pollution in America