There are some clouds in the sky,（）the sun is shining.

How are tornadoes distinguished from whirlwinds？

A．Whirlwinds rotate in a different direction than tornadoes do.

B．Tornadoes travel over land and whirlwinds over water.

C．Tornadoes are larger than whirlwinds.

D．Only tornadoes are funnel-shaped.

When you look up at the night sky, what do you see？ There are other(26)_____bodies out there besides the moon and stars. One of the most(27)_____of these is a comet.

Comets were formed around the same time the Earth was formed. They are(28)_____ice and other frozen liquids and gases.(29)_____these "dirty snowballs" begin to orbit the sun, just as the planets do.

As a comet gets closer to the sun, some gases in it begin to unfreeze. They(30)_____dust particles from the comet to form. a huge cloud. As the comet gets even nearer to the sun, a solar wind blows the cloud behind the comet, thus forming its tail. The tail and the(31)_____fuzzy atmosphere around a comet are(32)_____that can help identify this(33)_____in the night sky.

In any given year, about a dozen known comets come close to the sun in their orbits. The average person can’t see them all, of course. Usually there is only one or two a year bright enough to be seen with the(34)_____eye. Comet Hale-Bopp, discovered in 1995, was an unusually bright comet. Its orbit brought it(35)_____close to the Earth, within 122 million miles of it. But Hale-Bopp came a long way on its earthly visit. It won’t be back for another four thousand years or so.

massive stars in a few localized regions requires that star formation somehow be

coordinated over long periods of time. The process commences with a single O-

Line type star or a cluster of such stars in a giant molecular cloud, around which

(5) stellar radiation, winds and explosions carve a modest cavity from of the

surrounding interstellar medium, concomitantly destroying the progenitor

cloud. Perchance this disturbance triggers star formation in a nearby cloud, and

so on, until the interstellar medium in this corner of the galaxy resembles Swiss

cheese, composed of what theorists have recently begun to refer to as bubbles,

(10) or superbubbles, one of the most exciting discoveries in astrophysics in years.

Within a hot bubble, the sun has revealed itself in x-rays emitted by highly

ionized trace ions such as oxygen and at some point in the process of its

formation, nearby bubbles commence to overlap, coalescing into a superbubble.

The energy from more and more O-type stars feeds this expanding superbubble

(15) until its natural buoyancy stretches it from the midplane up toward the halo,

forming a chimney-the superbubble thus becomes a pathway for hot interior

gas to spread into the upper reaches of the galactic atmosphere, producing a

widespread corona. Far from its source of energy, the coronal gas slowly starts

to cool and condense into clouds. Over cons, these clouds fall back to the

(20) galaxy's mid-plane, completing the fountain-like cycle and replenishing the

galactic disk with cool clouds from which star formation begins anew.

Star formation often occurs in sporadic but intense bursts, but in the Milky

Way the competing feedback effects almost balance out, so that stars form. at an

unhurried pace-just 10 per year on average, except in some galaxies where

(25) positive feedback has gained the upper hand. 20 million to 50 million years ago,

star formation in the central parts of M82 began running out of control. Our

galaxy, too, may have had sporadic bursts, and the way these starbursts occur,

and what turns them off must be tied to the complex relation between stars and

the tenuous atmosphere from which they precipitate.

(30) Progress will be made in this complicated subject as astronomers continue

to study how the medium is cycled through stars, through the different phases

of the medium, and between the disk and the halo. Observations of other

galaxies give astronomers a bird' s-eye view of the interstellar goings-on, and

answer such a critical question as whether stars are really the main source of

(35) power for the interstellar medium. The loop above the Cassiopeia superbubble

looks uncomfortably similar to the prominences that arch above the surface of

the sun, prominences which owe much to the magnetic field in the solar

atmosphere, and scientists have begun to wonder if magnetic activity dominates

our galaxy's atmosphere.

The primary function of the passage as a whole is to

A．indicate the direction that research into a particular physical phenomenon should take

B．illustrate the limitations of applying mathematics to complicated astrophysical phenomena

C．clarify the differences between an old explanation of a physical phenomenon and a new model of it

D．introduce a new explanation of a physical phenomenon

E．explain the difference between two related physical phenomena

Evolution is mostly to blame. It has designed mankind to cope with deprivation, not plenty. People are perfectly tuned to store energy in good years to see them through lean ones. But when bad times never come, they are stuck with that energy, stored around their expanding bellies.

Thanks to rising agricultural productivity, lean years are rarer all over the globe. Modernday Malthusians, who used to draw graphs proving that the world was shortly going to run out of food, have gone rather quiet lately. According to the UN, the number of people short of food fell from 920m in 1980 to 799m 20 years later, even though the world's population increased by 1.6 billion over the period. This is mostly a cause for celebration. Mankind has won what was, for most of his time on this planet, his biggest battle: to ensure that he and his offspring had enough to eat. But every silver lining has a cloud, and the consequence of prosperity is a new plague that brings with it a

host of interesting policy dilemmas.

As a scourge of the modern world, obesity has an image problem. It is easier to associate with Father Christmas than with the four horses of the apocalypse. But it has a good claim to lumber along beside them, for it is the world's biggest public-health issue today—the main cause of heart disease, which kills more people these days than AIDS, malaria, war; the principal risk factor in diabetes; heavily implicated in cancer and other diseases. Since the World Health Organisation labelled obesity an "epidemic" in 2000, reports on its fearful consequences have come thick and fast.

Will public-health warnings, combined with media pressure, persuade people to get thinner, just as they finally put them off tobacco？ Possibly. In the rich world, sales of healthier foods are booming (see survey) and new figures suggest that over the past year Americans got very slightly thinner for the first time in recorded history. But even if Americans are losing a few ounces, it will be many years before the country solves the health problems caused by half a century's dining to excess. And, everywhere else in the world, people are still piling on the pounds. That's why there is now a consensus among doctors that governments should do something to stop them.

The author write this passage mainly to ______.

A．bring up some warnings.

B．tell the reader some new facts.

C．discuss a solution to a problem.

D．persuade the reader to keep fit.

A.Spring Cloud Security

B.Spring Cloud Eureka

C.Spring Cloud Bus

D.Spring Cloud Data Flow

A.Cloud PC

B.Cloud Gaming

C.Cloud VR/AR

D.远程抄表

云计算的英文是Cloud Computing。()

A. 路由器

B. Cloud Controller

C. UAA

D. Health Manager

A.CSA-STAR

B.Trusted Cloud

C.TUV Trusted Cloud

D.ISO27001

E.德国PSA

【24】______ , there is an unwritten but clearly understood code of behavior. which, 【25】______ broken, makes the offender immediately the object of 【26】______ .

It has been known as a fact that a British has a 【27】______ for the discussion of their weather and that, if given a chance, he will talk about it 【28】______ . Some people argue that it is because the British weather seldom 【29】______ forecast and hence becomes a source of interest and 【30】______ to everyone. This may be so. 【31】______ a British cannot have much 【32】______ in the weathermen, who, alter promising fine, sunny weather for the following day, are often proved wrong 【33】______ a cloud over the Atlantic brings rainy weather to all districts! The man in the street seems to be as accurate -- or as inaccurate -- as the weathermen in his 【34】______ .

Foreigners may be surprised at the number of references 【35】______ weather that the British make to each other in the course of a single day. Very often conversational greetings are 【36】______ by comments on the weather. "Nice day, isn't it？" "Beautiful day!" may well be heard instead of "Good morning, how are you？" 【37】______ the foreigner may consider this exaggerated and comic, it is worthwhile pointing out that it could be used to his advantage. 【38】______ he wants to start a conversation with a British but is 【39】______ to know where to begin, he could do well to mention the state of the weather. It is a sale subject which will 【40】______ an answer from even the most reserved of the British.

【21】

A．relaxed

B．frustrated

C．amused

D．exhausted