天文学家发现某恒星有一颗行星在圆形轨道上绕其运动,并测出了行星的轨道半径和运动周

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问题:

天文学家发现某恒星有一颗行星在圆形轨道上绕其运动,并测出了行星的轨道半径和运动周期.由此可推算出

考点:万有引力定律
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常用干燥的方法主要有()。

A.常温低露点空气或氮气干燥

B.热空气循环干燥

C.热氮循环干燥

D.溶剂吸收法干燥

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关于木炭、一氧化碳、氢气分别与氧化铜的反应,下列说法错误的是(  )

A.都有红色物质生成

B.都有还原剂参加反应

C.都是置换反应

D.反应都需要加热或高温

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Ⅰ型神经纤维瘤病的临床表现有()

A.成人周身5个咖啡牛奶斑和1个丛状神经纤维瘤

B.腹股沟雀斑样痣和1个皮肤型神经纤维瘤

C.1个虹膜错构瘤(Lisch结节)且祖父为神经纤维瘤病患者

D.视神经胶质瘤且蝶骨发育不良

E.1个丛状神经纤维瘤和腋窝雀斑样痣

题型:选择题

BEIJING, Jan. 11(Xinhuanet)-- Sleeping a little bit longer a day might help fight against obesity(肥胖), a recent study shows. The research-- published in the Archives of Internal Medicine along with an editorial by Turek and Northwestern colleague Joseph Bass commenting on it and related research-- after comparing people of normal weight- a body mass index of less than 25- with those who were overweight or obese , found that sleeping for an extra 20 minutes each night could offer a pain-free way to lose weight.

Insufficient sleep is linked with changes in hormone levels that may stimulate(刺激)appetite. A series of studies in recent months have shown that the less people sleep, the heavier they tend to be.

American researcher Robert Vorona from Eastern Virginia Medical School in Norfolk and colleagues have now examined the relationship between people's self-reported sleep time per 24 hours and their body mass index(BMI). They found that total sleep time and BMI were inversely correlated was total sleep time decreased, BMI increased, except in the severely obese group." Americans experience insufficient sleep and corpulent bodies. Clinicians are aware of the burden of obesity on patients," the study said. "Our findings suggest that major extensions of sleep time may not be necessary, as an extra 20 minutes of sleep per night seems to be associated with a lower body mass index," it added. "We warn that this study does not establish a cause-and-effect relationship between restricted sleep and obesity (but) investigations demonstrating success in weight loss via extensions of sleep would help greatly to establish such a relationship."

In November 2004, researchers from Columbia University in New York City, New York demonstrated a clear link between the risk of being obese and hours of nightly sleep, finding that people aged 32 to 59 who slept four hours or less per night were 73% more likely to be obese than people who slept between seven and nine hours per night.

小题1:The research, which was published in the Archives of Internal Medicine, found that____________.

sleeping for a shorter time a day might help fight agianst obesity

an extra 20 minutes’ sleep each night could offer a way to lose weight wothout pain

total sleep time and body mass index were inversely related

people aged 32 to 59 who slept four hours or less per night were 73% more likely to be obese than people who slept between seven and nine hours per night

小题2:How many research results are presented in the text?

A.Two

B.Three

C.Four

D.Five小题3: What does the underlined word “obses” probably mean?

A.thin

B.fat

C.energetic

D.painful小题4:According to the text , the author intends to tell us that _____________________.

A.Sleeping a little bit longer a day might help fight against obesity

B.insufficient sleep is linked with changes in hormone lives

C.there exists a clear link between the risk of being obeses and hours of nightly sleep

D.the less people sleep , the heavier they tend to be

题型:选择题

在矿井生产过程中所产生的各种()统称为矿尘。

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