题目内容
A
：This box is too heavy for me.B
：:Don't ________! I'll help you.[
]A
．sorry B．excuse C．worry D．look
名校课堂系列答案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.
| A．lighter than | B．heavier than | C．no heavier than | D．as heavy as |
【小题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 |
Taking away a city’s rubbish is a big job. Every day trucks come into a city to collect it. Most rubbish is made up of things we can’t eat or use. If we kept these things we would soon have a mountain of rubbish.
In some cities the rubbish is collected and taken outside of the city to a dump(垃圾站). Often the city dump is placed where the ground is low or there is a big hole. The kitchen rubbish is broken into small pieces and sent into the sewage system. The sewagesystem takes away the used water from toilets, bathtubs(澡盆) and other places.
To keep mice and flies away, some earth is used to cover the newly dumped rubbish. Later, grass may be planted on the rubbish-filled land. Finally, a house or a school may be built there, and then you’d never know that this had once been an old rubbish dump.
In other cities the rubbish is burnt in special places. The fire burns everything but the metal. Sometimes the metal can be used again in factories where things are made of metal. The food parts of rubbish are put in special piles where they slowly change into something called humus(腐殖土), which looks like black earth. It is rich with kinds of things that feed plants and help make them grow.
【小题1】You can most probably read the passage in _______.
| A．a history book | B．a TV guide |
| C．a science book | D．a telephone book |
| A．排污 | B．染色 | C．洗涤 | D．吸尘 |
| A．to feed animals |
| B．to feed plants |
| C．to build a house |
| D．to make machines |
| A．By burning it off. |
| B．By putting it in water. |
| C．By throwing it away. |
| D．By reusing and recycling it. |
Taking away a city’s rubbish is a big job. Every day trucks come into a city to collect it. Most rubbish is made up of things we can’t eat or use. If we kept these things we would soon have a mountain of rubbish.
In some cities the rubbish is collected and taken outside of the city to a dump(垃圾站). Often the city dump is placed where the ground is low or there is a big hole. The kitchen rubbish is broken into small pieces and sent into the sewage system. The sewage system takes away the used water from toilets, bathtubs(澡盆) and other places.
To keep mice and flies away, some earth is used to cover the newly dumped rubbish. Later, grass may be planted on the rubbish-filled land. Finally, a house or a school may be built there, and then you’d never know that this had once been an old rubbish dump.
In other cities the rubbish is burnt in special places. The fire burns everything but the metal. Sometimes the metal can be used again in factories where things are made of metal. The food parts of rubbish are put in special piles where they slowly change into something called humus(腐殖土), which looks like black earth. It is rich with kinds of things that feed plants and help make them grow.
【小题1】You can most probably read the passage in _______.
| A．a history book | B．a TV guide |
| C．a science book | D．a telephone book |
| A．排污 | B．染色 | C．洗涤 | D．吸尘 |
| A．By burning it off. | B．By putting it in water. |
| C．By throwing it away. | D．By reusing and recycling it. |