Every object has weight. But the center of its weight is not always in the middle of the object. If the top of an object is heavier than its bottom, it will fall over easily. We say that its center of gravity is high. But if the bottom is heavier, it won’t fall easily. Then we say that its center of gravity is low.

Look at the first picture. This empty box must fall over, because its center of gravity (C) is not above the line of its bottom (AB).

Now look at the second picture. There is some heavy iron in the bottom of this box. It will not fall, because its center of gravity is above its bottom.

1.If the bottom of an object is ______ its top, it will fall over easily.

A. lighter than　　 B. heavier than　　 C. no heavier than　　  D. as heavy as

2.Please point out which box will not fall.

3.The main idea of the passage is _________.

A. why things fall over　　　　         B. a low center of gravity

C. a high center of gravity　　             D. that everything has weight

1.据说哈利波特已经出版了。

It is said that Harry Potter has     ▲         ▲    .

2.在我等车的时候，我睡着了。

While I was waiting for the bus , I     ▲          ▲    .

3.你参观过的地方被用亮紫色作上了记号。

The places you have visited are     ▲         ▲     bright purple .

4. 太空山外人们排的队不见尽头。

The line of people outside the Space Mountain was     ▲    .

5.过山车高速移动，我们都很害怕。

The roller coaster moved     ▲        ▲ _    ▲   , we were very afraid.

6.我们太激动了，以至于很长时间不停地为她鼓掌。

We were     ▲        ▲        ▲    we couldn’t stop clapping our hands for her .

7.北京的天气和广东大不一样。

The weather in Beijing was quite     ▲   from     ▲    in Guangdong .

Every object has weight. But the center of its weight is not always in the middle of the object. If the top of an object is heavier than its bottom, it will fall over easily. We say that its center of gravity is high. But if the bottom is heavier, it won’t fall easily. Then we say that its center of gravity is low.
Look at the first picture. This empty box must fall over, because its center of gravity (C) is not above the line of its bottom (AB).
Now look at the second picture. There is some heavy iron in the bottom of this box. It will not fall, because its center of gravity is above its bottom.

【小题1】If the bottom of an object is ______ its top, it will fall over easily.

Do you know that a fast reader can get the ideas better than a slow reader can? Of course, you save time by reading fast, but this is not the main reason for fast reading. The main reason is that you understand better what you are reading when you read fast.

As your eyes move along the line of point, they make fixations (固定) or pauses (暂停). It is important that you see several words at a fixation. It is also important that your eyes leave a group. The numbers of letters or words that you see at a fixation are called your eye span (视跨). Pay more attention to improving your rate of reading. With practice you can learn to read faster than you usually read.

The way in which you read always depends on (取决于) what you are reading and for what purpose. You should know the different ways of reading so that you can apply whatever method is necessary. Here are four ways of reading:

(1) Skimming is an important kind of reading. This method can be used when you wish to review something that you have forgotten. You can skim to get the main points.

(2) Rapid (快速) first reading and then rereading certain parts carefully is important. You may use this type of reading to study a science lesson or a history lesson.

(3) You need to do careful reading and rereading sometimes. This type of reading is necessary for making an intensive (细致的) study of your school subjects, solving math problems or reading directions.

(4) Rapid reading is used when reading stories for enjoyment. You may also do rapid reading when reviewing materials that you already know well.

1.The main reason for reading fast is that you can ________.

A．get the ideas       B．save time          C．understand better   D．learn well

2.The way of reading always depends on ________.

A．the method that you like                  B．your reading material

C．your reading purpose                    D．both B and C

3.The word “skimming” means “________”.

A．reading the main points                  B．reading carefully

C．reading very fast                        D．reading some parts of the material

4.Careful reading is an important kind of reading ________.

A．when you review a lesson that you already know well

B．when you read the directions before using a camera which is expensive

C．when you read a story of enjoyment

D．when you wish to find a lost place that you have read