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问题 单项选择题

抑郁症的“三无”症状是（）。

A．无食欲、无望和无价值 

B．无望、无助和无价值 

C．无望、无助和无兴趣 

D．无兴趣、无助和无价值 

E．无望、无力和无价值

答案

参考答案：B

解析：

“三无”症状即无望、无助和无价值。所谓无望是指患者对自己的现在和未来都感到没有信心、失望甚至是绝望；无助是指患者感到自己孤立无援，尽管周围的人都在给予关心和帮助；无价值是指患者感到自己的存在无论对自己、对家庭还是对社会都没有任何价值。

单项选择题

马汉认为海军是（），重要的使命是支持和推动国家的对外政策。

A.突击性军种

B.革命性军种

C.国际性军种

D.防御性军种
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单项选择题

The sun today is a yellow dwarf star. It is fueled by thermonuclear reactions near its center that convert hydrogen to helium. The sun has existed in its present state for about 4 billion, 600 million years and is thousands of times larger than the Earth.
By studying other stars, astronomers can predict what the rest of the sun’s life will be like. About 5 billion years from now, the core of the sun will shrink and become hotter. The surface temperature will fail. The higher temperature of the center will increase the rate of thermonuclear reactions. The outer regions of the sun will expand approximately 35 million miles, about the distance to mercury, which is the closest planet to the sun. The sun will then be a red giant star. Temperatures on the earth will become too hot for life to exist.
Once the sun has used up its thermonuclear energy as a red giant, it will begin to shrink. After it shrinks to the size of the earth, it will become a white dwarf star. The sun may throw off huge amounts of gases in violent eruptions called nova explosions as it changes from a red giant to a white dwarf.
After billions of years as a white dwarf, the Sun will have used up all its fuel and will have lost its heat. Such a star is called a black dwarf. After the Sun has become a black dwarf, the earth will be dark and cold. If any atmosphere remains there, it will have frozen onto the earth’s surface.

It can be inferred from the passage that the sun ______ .

A．is approximately halfway through its life as a yellow dwarf
B．has been in existence for 10 billion years
C．is rapidly changing in size and brightness
D．will continue as a yellow dwarf for another 10 billion years
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