题目内容
（请给出正确答案）
______lie(s)between the boundary of Canada and the U. S. and serve(s)as the boundary between the two countries.
A．The Mississippi River
B．The Great Lakes
C．The Rocky Mountains
D．The Grand Canyon
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更多“______lie（s)between the boundary of Canada and the U. S. and serve（s)as the boundary betwe”相关的问题
A.identity
B.language
C.population
D.sports
A.safe lie always float
B.safely lie always float
C.safe lie always afloat
D.safely lie always afloat
Compared with their cosmologist(宇宙学家) colleagues, cosmogonists(星源学家) can sound a little old-fashioned. Edgar Allen Poe turned to the mysteries of cosmogony in an 1848 public lecture, just reprinted by Hesperus Press. And we encountered a reference to cosmogonists most recently in a new edition of Poe's prose poem Eureka.
What's the difference between cosmologists and cosmogonists？ Just two letters and a few billion light years. Cosmologists worry about where the Universe came from, cosmogonists with how the Solar System formed. The interesting thing is that one-and-a-half centuries after Poe, they still can't reach agreement on what happened in the nearest 5 light years of space.
What's the problem？ It turns out that there are a couple of competing explanations for why our neighbourhood is the shape it is, as well as several bizarre anomalies in the data. Cosmogonists know that the Solar System is essentially flat. With the exception of two tiny outliers, Mercury and Pluto, the orbits of all the other planets lie in very nearly the same plane. And most cosmogonists agree that this is because the planets themselves formed from a nebular(星云状的)disc orbiting the early Sun, which had itself coalesced out of the same cloud of gas and dust.
But there's a catch. If the planets and the Sun came from the same nebular disc, then the Sun's equator should lie in the planetary plane. It doesn't. The Sun leans over at an angle of 7.25° The majority of cosmogonists insist that the angle is so close to zero that it really doesn't matter. Anyway, they add, the Sun has been losing mass for most of its life, and may have slipped a little.
The remaining minority aren't having this. How can 7.25° be the same as zero？ The Sun and the planets did come from cosmic dust, they say, but not from the same cloud of material. The Sun took shape somewhere in the Galaxy. Then it sailed along and picked up the planets—or perhaps the gas and dust that gave birth to them—elsewhere.
Is a tilting Sun the cosmogonists' only headache？ Not at all. It's also hard to agree on how the outer planets formed. Far out in the nebular disc, matter would have been so spread out that it couldn't quickly have dumped together. Some suggest planet-sized gravitational instabilities, others can find no reason for Uranus and Neptune to have formed yet.
The closer you get to home, it seems, the deeper the mysteries.
What is the best title for the passage？
A．Difference Between Cosmologist and Cosmogonist.
B．Where the Universe Came From.
C．How the Solar System Formed.
D．The Titling Sun.
A．efficiency
B．location
C．Setup CDs
D．attitude
Since 1957, a team of researchers has monitored the dietary habits and medical histories of 2,000 middle-aged men employed by the Western Electric Co. in Chicago. Led by Dr. Pritichard Shekelle of Chicago's Rush--Presbyterian--St. Luke's medical Centre, the team recently began to sort out the links between the subjects' dietary patterns and cancer. Other animal and human studies has suggested that vitamin A might offer some protection against lung cancer, but did not distinguish vitamin A made in the body from that in carotene (胡萝卜素), which is abundant in a variety of vegetables and fruits, including carrots, spinach, broccoli, squash, tomatoes and apples.
The Western Electric study showed little correlation (相互关系)between the incidence of lung cancer and the consumption of foods containing performed vitamin A. But the data on carotene intake (摄入)revealed a significant relationship. Among the 488 men who had the lowest carotene consumption, there were 14 cases of lung cancer; in a group of the same size that ate the most carotene, only two eases developed. The apparent protective effect of carotene held up even for long-time smokers.
Further studies will be necessary before the link between lung cancer and carotene can be firmly established. Meanwhile, researchers warn against taking large amounts of vitamin-A supplements, which can be extremely poisonous in high doses. Instead, they advise a well-balanced diet that includes foods rich in carotene.
Vitamin A can be found in meat.
A．Right
B．Wrong
C．Not mentioned
A．nature of activity.
B．option of withdrawal.
C．legitimacy of activity.
D．power distribution.
A.Permalloyed
B.Destroyed
C.Deployed
D.employed
A．efficiency
B．location
C．setup CDs
D．attitude
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