以下对青春期描述不正确的是（）。-我要搜题网

[单项选择]腰椎正位摄影，中心线入射点应是
A. 胸骨剑突的末端
B. 剑突与脐连线中点
C. 肚脐上方3cm
D. 肚脐下方3cm
E. 耻骨联合的上缘

[判断题]对有限空间进行初次气体检测或者不能确定空间内有毒有害气体浓度时，救援人员必须全程佩戴氧气呼吸器。作业时间长且环境条件允许情况下，可佩戴使用氧气呼吸器。
A.正确
B.错误

[判断题]进站、接车进路信号机和自动闭塞区间并置的通过信号机处，钢轨绝缘可装在信号机前方或后方各2m的范围内。（）
A.正确
B.错误

[不定项选择题]共用题干 New Comet Found

There's a newfound comet closing in on the sun,and when it gets here in 2013,you may be able to see it with your naked eye.
Astronomers stumbled upon the icy interloper on June 5 while searching for potentially hazardous asteroids（小行星）.Equipped with the world's largest digital camera , the University of Hawaii's Pan-STARRS team snagged a faint image of the odd object while it was more than 700 million miles away , between the orbits of Jupiter（木星）and Saturn（土星）.
"Almost everything we find is an asteroid,but this object was suspicious,"said Richard Wainscoat,co-discoverer of the comet and an astronomer at the University of Hawaii."Unlike asteroids, which appear point-like in images,the telltale sign that gave it away was its fuzzy appearance."
By March 2013 the comet,named C/2011 L4(PANSTARRS),is expected to come within 30 million miles of the sun一closer even than the innermost（最深处）planet, Mercury（水星）.
When the comet makes its closest approach to the sun,most of its ices will vaporize,adding to its hazy envelope of gas and dust and producing the familiar tail. This denser envelope,or coma, should boost the comet to peak brightness,making it potentially visible to the naked eye low in the western horizon just after sunset.
While there is no danger of collision with Earth,preliminary calculations of the comet's orbit show that this may be its first and final trip through the solar system."It may be coming around the sun for the first and only time,only to be ejected from the solar system,never to return,"Wainscoat said."Since we don't have a lot of data on it,we really don't know the orbit well enough right now, and it will take up to two months of observations to find out."
Astronomers believe C/2011 L4 may be a runaway from the Oort cloud（奥尔特云）,a reservoir of billions of hibernating（蛰伏）comets that orbits about 100,000 times farther than the distance between Earth and the sun.
The fact that it's going around the back of the sun from our point of view may ultimately affect the comet's visibility,but a lot will depend on how close the body actually gets to the sun.Also, whether the comet is north or south of the sun when it reaches peak brightness will determine which hemisphere on Earth gets the better view. Astronomers gets many details about the solar system.
A.Right
B.Wrong
C.Not mentiond

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