题目内容
When you hear the word quicksand, what image comes to mind? You probably picture someone up to the waist in wet land, screaming for help. In fact, quicksand can be very dangerous. People and animals have sunk into quicksand before and never escaped. However, the more you know about quicksand, the safer you will be.
First, quicksand is really ordinary sand. It isn’t some sort of strange hungry beast. Quicksand forms when water seeps up (渗出) from the underneath a layer of fine sand. The water pushes the grains of sand apart and makes the sand loose. This loose sand will not hold up a heavy weight.
Quicksand usually forms along the banks of rivers, at the seashore, or under slow-moving rivers and streams. It only forms when water flows upward through the sand, not over it. If you are in a place that tends to have quicksand, it’s a good idea to carry a large stick. As you walk, poke (戳) the ground in front of you to be sure it’s firm.
Let’s suppose that you happen to step into some quicksand. The best way to deal with it is to stay calm. You may sink, but you won’t sink quickly. You will have time to try several ways to get out. First, drop anything you might be carrying that adds weight, such as a backpack. Then try walking out -making slow and steady movements with your legs. If this doesn’t work, the best thing to do is lie back and float, it’s even easier to float on quicksand than on regular water.
Of course, you will want to call for help. If help is nearby, it’s best simply to wait. If help is not nearby, then continue to lie on your back but make slow, rolling movements toward the edge of the quicksand. When you feel solid ground underneath, you can stand up.
Some animals seem to know how to avoid sinking down into quicksand. Mules, for instance, fold their legs underneath them and float on their bellies. Cows, on the other hand, tend to panic and wave their legs around. This doesn’t help them escape. So, if you are ever trapped in quicksand, think like a mule, not like a cow.
56. What detail supports the idea that quicksand can be dangerous?
A. Quicksand forms when water seeps up from underneath.
B. You will have time to try several ways to get out.
C. Animals have fallen into quicksand and never escaped.
D. Quicksand is really just an ordinary sand.
57. If you get caught, what should you do first?
A. Wave your arms and legs quickly.
B. Drop anything heavy that you are carrying.
C. Fold your legs underneath you.
D. Poke a stick into the ground in front of you.
58. How is the mule’s reaction to quicksand different from a cow’s reaction?
A. Mules fold their legs and float on their bellies.
B. Mules wave their legs around.
C. Mules sink immediately.
D. Mules panic and splash their legs around.
59. What’s the passage about?
A. Quicksand is not really made up of sand.
B. Quicksand can be dangerous, but there are ways to escape.
C. You should poke the ground in front of you with a stick.
D. Animals are able to float on quicksand, but humans always sink.
60. The author’s main purpose in this passage is to _______________.
A. give information about quicksand
B. tell an entertaining story
C. persuade people to avoid quicksand
D. explain how quicksand forms
CBABA
China_is_going_green. In order to reduce air pollution and oilshortages, automobile manufacturers have announced their plans to develop hybrid vehicles (混合燃料汽车) for the Chinese market. Toyota's hybrid car Prius will be ready to drive in China this week. Let's have a look at the new car.
Any vehicle is a hybrid when it combines two or more sources of power. Hybrid cars run off a rechargeable battery and gasoline. Hybrid cars have special engines, which are smaller than traditional gasoline engines. They run at 99 percent of their power when the car is cruising (匀速行驶). A specially designed battery motor provides extra power for running up hills or when extra acceleration is needed.
Step into a Prius, and turn on the engine. The first thing you notice is how much quieter it is than a traditional car. At this point, the car's gasoline engine is dormant (休眠). The electric motor will provide power until the car reaches about 24 km/h. If you stay at a low speed, you are effectively driving an electric car, with no gasoline being used, and no waste gas gives off.
The onboard(车载的) computer makes the decision about when to use a gas engine, when to go electric, and when to use a combination of the two. If you go over 24 km/h, when you step on the gas pedal (油门), you are actually telling the computer how fast you want to go.
The electronic motor recharges automatically using a set of batteries. When driving at high speed, the gasoline engine not only powers the car, but also charges the batteries. Any time you use the brake, the electric motor in the wheels will work like a generator and produce electricity to recharge the batteries. As a consequence, the car's batteries will last for around 200,000 miles.
【小题1】The author writes this passage mainly to________.
A.teach people how to drive a hybrid car |
B.introduce a new kind of “green” car |
C.show how to save their gasoline when driving a car |
D.announce plans to develop hybrid vehicles for China |
A.there will be more and more green land in China |
B.China is still young and lacking experience |
C.China's new cars are combinations of different green models |
D.China has started producing environmentally friendly cars |
A.The hybrid cars reduce air pollution and oilshortages. |
B.The car's gasoline engine doesn't work until it reaches about 24 km/h. |
C.This kind of car is completely controlled by an onboard computer. |
D.A specially designed battery motor provides extra power when needed. |
A.They are powered by both a rechargeable battery and gasoline. |
B.They are much quieter than traditional cars. |
C.They only use 99 percent of their power to run up hills. |
D.They have smaller engines than traditional gasoline ones. |