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What makes rain fall？A．Air currents' movement.B．The earth gravity.C．Droplets' movementD．Th

What makes rain fall？

A．Air currents' movement.

B．The earth gravity.

C．Droplets' movement

D．The size of the droplets

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发布时间：2022-02-27

更多“What makes rain fall？A．Air currents' movement.B．The earth gravity.C．Droplets' movementD．Th”相关的问题

第1题

What makes it rain？ Rain falls from clouds for the same reason anything falls to Earth. Th

e Earth's Gravity(重力) pulls it. But every cloud is made of water droplets or ice crystals. Why doesn't rain or snow fall constantly from all clouds？ The droplets or ice crystals in clouds are exceedingly small. The effect of gravity on them is minute. Air currents move and lift droplets so that the net downward displacement is zero, even though the droplets are in constant motion.

Droplets and ice crystals behave somewhat like dust in the air made visible in a shaft(束) of sunlight. To the casual observer, dust seems to act in a totally random fashion, moving about wildly without fixed direction. But in fact dust particles are much larger than water droplets and they finally fall. The cloud droplet of average size is only 1/2,500 inch in diameter. (78)It is so small that it would take sixteen hours to fall half a mile in perfectly still air, and it does not fall out of moving air at all. Only when the droplet grows to a diameter of 1/125 inch or larger can it fall form. the cloud. The average raindrop contains a million times as much water as a tiny cloud droplet. The growth of a cloud droplet to a size large enough to fall out is the cause of rain.

What is the main topic of the passage？

A．The mechanics of rain.

B．The climate of North America.

C．How gravity affects air current.

D．Types of clouds.

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第2题

Considered as a continuous body of fluid, the atmosphere is another kind of ocean. Yet, in

view of the total amount of rain and snow on land areas in the course of a year, one of the most amazing water facts is the very small amount of water in the atmosphere at any given time. The volume of the lower seven miles of the atmosphere--the realm of weather events- is roughly four times the volume of the world's oceans. But the atmosphere contains very little water. It is chiefly in the form. of invisible vapor, some of which is carried over land by air currents. If all vapor suddenly fell from the air onto the earth's surface, it would form. a layer only about one inch thick. A heavy rainstorm on a given area may use up only a small percentage of the water from the air mass that passes over. How, then, can some land areas receive more than 400 inches of rain per year？ How can several inches of rain fall during a single storm in a few minutes or hours？ The answer is that rain yielding air masses are in motion, and as the driving air mass moves on, new moist air takes its place.

The basic source of most water vapor is the ocean, evaporation, vapor transport, and precipitation (陈雨) make up the continuous movement of water from ocean to atmosphere to land and back to the sea. Rivers return water the sea. In an underground arc (弧) of the cycle, flowing bodies of water discharge some water directly into rivers and some directly to the sea.

What might have been discussed before this passage？

A．The ocean.

B．The earth.

C．The rainfall.

D．The atmosphere.

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第3题

下列哪个句子中的“ fall”含义不同（）

A.One of the kids fall into the river

B.The rain was falling

C.mong the four seasons I like fall very much

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第4题

用小型开放模型预测，在下列每个事件时，贸易余额、实际汇率和名义汇率会发生什么变动。 a．消费者对未来的信心

用小型开放模型预测，在下列每个事件时，贸易余额、实际汇率和名义汇率会发生什么变动。

a．消费者对未来的信心下降引起消费者消费更少而储蓄增加；

b．引进丰田的新型生产线使消费者对外国汽车的偏好大于本国汽车；

c．引进自动取款机减少了货币需求。

Use the model of the small open economy to predict what would happen to the trade balance, the real exchange rate, and the nominal exchange rate in response to each of the following events.

a．A fall in consumer confidence about the future induces consumers to spend less and save more.

b．The introduction of a stylish line of Toyotas makes some consumers prefer foreign cars over domestic ears.

c．The introduction of automatic teller machines reduces the demand for money.

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第5题

All whales fall into two groups, those with teeth and those without. Both beluga and dolph

in belong to the suborder of toothed whales known as Odontoceti, along with porpoises, narwhals, pilot whales, killer whales and the largest toothed creature in the world, the sperm whale. Size differences among the Odontoceti are remarkable. A common porpoise will run only 4 or 5 feet in length and 300 pounds in weight; a sperm whale may be 10 times as long and 300 times as heavy. The beluga falls in between, weighing up to 2,000 pounds. And it does chirp. In fact, it makes a great variety of squeaking, whistling, and clicking sounds, which have earned it the name of sea canary.

The toothless, or baleen, whales belong to the suborder of Mysticeti. This is a group of generally large whales, formerly abundant in all the oceans of the world. Though reduced by hunting, most species are still found along the coasts of the United Stated and Canada. All but two of the Mysticeti reach 40 feet or more at maturity, with the blue whale running up to 100 feet and tipping the scales at up to 130 tons. This whale is by far the largest creature that has ever lived on earth, 4 times the weight of the largest dinosaur, 30 times that of an elephant.

With what topic is the passage mainly concerned？

A．Breeding habits of whales.

B．Differences between whales.

C．Efforts to preserve whales.

D．The intelligence of whales.

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第6题

—What'stheweatherlikeinNewYork—It's__（）

A.rain

B.rains

C.rainy

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第7题

What will happen to you, if you（）in your school work?

A.fall down

B.fall apart

C.fall off

D.fall behind

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第8题

What may happen to you, if you （） in your school work。

A.fall down

B.fall apart

C.fall off

D.fall behind

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第9题

— What's wrong？ — I ____ off from my bicycle.

A.fall

B.fell

C.falled

D.falls

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第10题

Everyone has got two personalities-the one that is shown to the world and the other that i

s secret and real. You don't show your secret personality when you're awake. Because you can control yourself. But when you're asleep, your sleeping position shows the real you. In a normal night, of course, people often change their position. The important position is the one you go to sleep in.

If you go to sleep on your back, you're a very open person. You usually believe people and you accept new things or new ideas easily. You don't like to make people sad, so you never express your real feeling. You're quite shy.

If you sleep on your stomach, you are a rather secretive person. You worry a lot and you always easily become sad. You usually live for today not tomorrow. This means that you enjoy having a good time.

If you sleep curled up, you are probably a very nervous person. You have a low opinion of yourself. You're shy and don't like meeting people. You prefer to be on your own. You're easily hurt.

If you sleep on your side, you have usually got a well-balanced personality. You know your strengths and weaknesses. You're usually careful. You don't often get sad. You always say what you think even if it makes other people unhappy.

When do you show your secret personality？

A．When you are awake.

B．When you fall into deep sleep.

C．The moment you go to sleep.

D．when you lie in bed.

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