护理人员的道德情感不包括（） A.对病人高度负责 B.对事业的无私奉献 C.

A black hole is a place in space where gravity pulls so much that even light cannot get out. The gravity is so strong because matter has been squeezed into a tiny space. This can happen when a star is dying.

Because no light can get out, people can’t see black holes. Space telescopes with special tools can help find black holes. The special tools can see how stars that are very close to black holes act differently from other ones.

Black holes can be big or small. Scientists think the smallest black holes are as small as just one atom. These black holes are very tiny but have the mass of a large mountain. Mass is the amount of matter, or “staff”, in an object.

Another kind of black hole is called “stellar”(星球黑洞). Its mass can be up to 20 times more than the mass of the sun. There may be many stellar mass black holes in Earth’s galaxy. Earth’s galaxy is called the Milky Way.

The largest black holes are called “supermassive”(超大质量黑洞). These black holes have masses that are more than one million suns together. Scientists have found proof that every large galaxy contains a supermassive black hole at its center. The supermassive black hole at the center of the Milky Way galaxy has a mass equal to about four million suns and would fit inside a very large ball that could hold a few million Earths.

Scientists think the smallest black holes formed when the universe began. Stellar black holes are made when the center of a very big star falls in upon itself, or falls apart. When this happens, it exploded part of the star into space. Scientists think supermassive black holes were made at the same time as the galaxy they are in.

A black hole can not be seen because strong gravity pulls all of the light into the middle of the black hole. But scientists can see how the strong gravity affects the stars and gas around the black hole. Scientists can study stars to find out if they are flying around, or orbiting a black hole.

When a black hole and a star are close together, high-energy light is made. This kind of light cannot be seen with human eyes. Scientists use satellites and telescopes in space to see the high-energy light.

小题1:The gravity of a black hole may become so strong that light cannot get out when ____________.

A．the star is going to die

B．special tools are used on it

C．other stars come close to it

D．it is seen from the space telescopes小题2:According to the passage, which of the following is NOT true?

A．A black hole can be very tiny but extremely heavy.

B．The gravity of a black hole holds all light in its center.

C．Scientists observe high-energy light through their own eyes.

D．Some small black holes came into being as early as the universe.小题3:The underlined word “galaxy” in Paragraph 5 means __________.

A．a black hole

B．the Milky Way

C．a series of stars

D．a planet near the earth小题4:What does the last sentence in Paragraph 5 suggest?

A．Neither the sun nor the earth is as heavy as a black hole.

B．There is a supermassive black hole at the center of the Milky Way.

C．The supermassive black hole had existed before the Milky Way was formed.

D．There is a reason why the large black holes are called “supermassive”.小题5:The last two paragraph mainly focus on the question of _________.

A．what a black hole is

B．how black holes form

C．how big black holes are

D．how scientists know about black holes

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甲委托乙销售一批首饰并交付，乙经甲同意转委托给丙。丙以其名义与丁签订买卖合同，约定将这批首饰以高于市场价10%的价格卖给丁，并赠其一批箱包。丙因此与戊签订箱包买卖合同。丙依约向丁交付首饰，但因戊不能向丙交付箱包，导致丙无法向丁交付箱包。丁拒绝向丙支付首饰款。下列哪一表述是正确的？（ ）（2011年卷三单选第4题）

A．乙的转委托行为无效

B．丙与丁签订的买卖合同直接约束甲和丁

C．丙应向甲披露丁，甲可以行使丙对丁的权利

D．丙应向丁披露戊，丁可以行使丙对戊的权利

下列属于抑制细胞增殖的生长因子的是（）

A、TGF-β

B、表皮生长因子

C、胰岛素样生长因子

D、血小板衍生生长因子

在运转过程中，加氢催化剂活性下降，可通过（）来弥补。

A、提高反应温度

B、降低反应温度

C、提高反应压力

D、降低反应压力