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[主观题]

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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发布时间：2022-02-28

更多“What makes it rain？ Rain falls from clouds for the same reason anything falls to Earth. Th”相关的问题

第1题

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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第2题

—What'stheweatherlikeinNewYork—It's__（）

A.rain

B.rains

C.rainy

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第3题

What were Gore's findings from his scientific expedition in the Amazon Rain Forest

A.the deforestation of the Amazon

B.the destruction of biodiversity

C.the desertification of the Amazon

D.the rare species of birds

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第4题

Questionsare based on the following passage. When you think about the growth of human popu

Questionsare based on the following passage.

When you think about the growth of human population over the last century or so， it is alltoo easy to imagine it merely as an increase in the number of humans. But as we（36）， so doall the things associated with us，（37）our livestock （家畜）. At present， there are about 1.5 bil-lion cattle and domestic buffalo and about 1.7 billion sheep and goats. With pigs and poultry，they form. a（38）part of our enormous biological footprint upon this planet.

Just how enormous was not really apparent until the（39）of a new report， called "Live-stock"s Long Shadow，" by the Food and Agriculture Organisation of the United Nations.

Consider these numbers. Global livestock grazing （放牧） and feed production use "30percent of the land surface of the planet." Livestock —— which consume more food thanthey（40）—— also compete directly with humans for water. And the drive to expand grazingland destroys more biologically sensitive terrain， rain forests（41）， than anything else.

But what is even more striking， and alarming， is that livestock are（42）for about 18 per-cent of the global warming effect， more than transportation"s（43）. The culprits （罪魁祸首）are methane —— the natural result of bovine digestion —— and the nitrogen emitted by manure.

Deforestation of grazing land adds to the effect.

There are no easy trade-offs when it comes to global warming —— such as cutting back oncattle to make room for cars. The human（44）for meat is certainly not about to end anytimesoon. As "Livestock"s Long Shadow" makes clear， our health and the health of the planet de-pend on pushing livestock production in more（45）directions.

A．publication

B．waste

C．contribution

D．certainly

E. yield

F. multiply

G. critical

H. passion

I . concerning

J . available

K. liable

L. sustainable

K. responsible

N. including

O.especially

第（36）题应填__________

查看材料

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第5题

What makes the space shuttle ______ is that it takes off like a rocket but lands like an a

irplane.

A．exceptional

B．strange

C．unique

D．rare

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第6题

What（) you（) he’ s the murderer？

A. make, think

B. makes, think

C. makes, to think

D. make, thinking

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第7题

What is a spill pipe（）

A.drainage pipe that carries rain or spray from an upper deck to a lower deck

B.pipe under the anchor windlass leading to the chain locker

C.chute，usually over the stern，to lead dumped garbage clear of the hull

D.n opening in the deck leading outside the hull

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第8题

What makes Cog special？A．It looks 1ike a mother．B．It behaves 1ike a child．C．It can

What makes Cog special？

A．It looks 1ike a mother．

B．It behaves 1ike a child．

C．It can imitate血e behavior. of a mother

D．It has a huge brain

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第9题

They did hear from each other! （), their last meet was already more than 22 years ago.

A.Believe it or not

B.That is to say

C.On the one hand

D.What makes it

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第10题

I am trying to understand _____ that makes him late for work again.

A.what it is

B.why it is

C.why it does

D.what it does

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