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【单选题】
Lunar sight-seeing trips and orbiting space hotels are within reach, moon walking astronaut Edwin'Buzz' Aldrin said last week, but some who favor space tourism worried about its 'giggle factor'. Astronomers have known for years that a source of intense energy emissions lies at the center of the Milky Way Galaxy, obscured from view by vast clouds of dust and gas. In February, 1992, researchers at the Max Planck Institute in Garching, Germany, reported evidence that the mysterious energy source is a gigantic black hole. Observations have shown that many strong energy sources lie at the heart of the Milky Way. One of them, called Sagittarius A, is thought to be the actual center of the Galaxy, the point about which the great spiral of stars rotates. Sagittarius A is a powerful emitter of radio waves and X-rays. Astronomers have considered two possible explanations for the identity of Sagittarius A. They theorized that it is either a compact duster of normal stars or a super-massive black hole containing as much as a million or more suns. The German scientists reported that they found strong evidence in support of the black hole explanation. The astronomers used a new telescope high in the Andes Mountains of Chile to obtain the sharpest images ever made of the region around Sagittarius A. The image shows that Sagittarius A is a single, small object rather than a duster of stars. The researchers also found that a bubble of gas is expanding outward from Sagittarius A. This expanding gas is similar in temperate, density, and composition to the jets of gas that astronomers have observed flow hag away from the centers of many other galaxies. Such jets are thought to be generated by accretion disks surrounding enormous black holes. Accretion disks are vast, swirling masses of gas and dust that give off titanic amounts of energy as they are sucked into the black hole. The similarity between the jets emitted by some galaxies and the gas bubble surrounding Sagittarius A supports the idea that Sagittarius A is a super-massive black hole. According to the German researchers, the energy source at the center of the Milky Way Galaxy ______.
A.
has been covered up by vast clouds of dust and gas
B.
still remains unknown to astronomers
C.
has proved to be a black hole
D.
actually provides power for the rotation of file great spiral of stars
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【简答题】计算机中的"图"一类是借助图像获取设备获得的,另一类是使用计算机绘制的,或者通常被称为________。
【单选题】The abbreviation WWNWS means ____.
A.
World Wide Number Watch Station
B.
World Wide Network Watch Service
C.
World Wide Network Warning Station
D.
World Wide Navigational Warming Service
【单选题】打开文件时,( )文件模式表示以写入模式打开文件,如果文件不存在则创建。
A.
r
B.
w
C.
a
D.
r+
【单选题】关于左心室的叙述,下列正确的是
A.
房室口有三尖瓣
B.
前尖瓣位于主动脉口的前外侧
C.
室壁较右心室薄
D.
与肺动脉相通
【单选题】The abbreviation WWNWS means_____.
A.
World Wide Network Warning Station
B.
World Wide Navigational Warning Service
C.
World Wide Number Watch Station
D.
World Wide Network Watch Service
【单选题】The WWNWS is a coordinated global service for the broadcast by radio of vital information on() to marine navigation
A.
ship' s movement
B.
ship' s management
C.
safety
D.
hazards
【多选题】频数分析中常用的统计图包括( )
A.
直方图
B.
条形图
C.
饼图
D.
树形图
【单选题】频数分析中常用的统计图包括( )
A.
直方图
B.
柱形图
C.
饼图
D.
树形图
【多选题】关于右心室双出口(DORV),叙述正确的有()
A.
两侧半月瓣下肌性圆锥(双圆锥结构)是右心室双出口(DORV)必备解剖特征
B.
室间隔缺损(VSD.作为左心室的惟一出口,在DORV中也是必备的解剖特征
C.
Taussig-Bing畸形常合并主动脉弓病变,如主动脉峡部缩窄,主动脉弓发育不良及主动脉弓中断
D.
DORV合并主动脉瓣下VSD不伴肺动脉狭窄者,其血流动力学表现与单纯大型VSD相似,易出现早期充血性心力衰竭的表现
E.
DORV的手术方式选择主要与VSD位置及大动脉空间位置关系有关,与三尖瓣和肺动脉瓣的位置无关
【简答题】WWNWS
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