Question

If you look at the night sky, you’ll often see stars moving very quickly. In fact, they move much more quickly than they should according to their size and the laws of physics.

Scientists do not completely understand why the speed of these stars is so high. But many believe the reason is that much of the universe is made of something called “dark matter”. Groups of stars called galaxies, such as the Milky Way, might even be made up of 90 percent dark matter.

How much something weighs depends on where it is. The same object weighs only half as much on Mars as it does on Earth and almost three times as much on Jupiter. So scientists prefer to talk about the mass (质量) of something rather than how much it weighs, because mass does not change. They can work out the mass of galaxies by measuring the distance between them and the speed they move at.

Recently, Jorge Peñarrubia, a senior academic at Edinburgh University, UK, and his team discovered something interesting: The mass of the Milky Way is only half as much as the mass of another nearby galaxy, Andromeda. This seems strange, and dark matter may explain why.

Finding out more about dark matter could help us understand how the universe began, but this is not easy. Lots of scientists with different types of expert knowledge are working on the problem.

We can’t see dark matter, it’s very difficult to measure and we can’t find out its mass. Unlike stars, dark matter doesn’t produce or reflect light. But we can make a good guess that it is there because of the way things move and the way light bends. Experts now think dark matter may be very different from the matter that we find on Earth. There may also be five times as much dark matter in the universe as ordinary matter.

1.Something that weighs 15kg on Earth weighs about ________ on Mars and ________ on Jupiter.

A. 7.5 kg, 45 kgB. 30 kg, 45 kgC. 45 kg, 7.5 kgD. 5 kg, 30 kg

2.The author mentions the masses of the Milky Way and Andromeda mainly to ________.

A. explain why the same object has a different weight on different stars

B. compare the distance between the Milky Way and Andromeda

C. show that studying dark matter could help to answer some scientific questions

D. support the idea that scientists prefer to talk about mass instead of weight

3.Dark matter is difficult to investigate because ________.

A. it travels at a very fast speed

B. we can’t see where it is or measure its mass

C. it’s hard to measure the light it produces and reflects

D. it is much bigger than ordinary matter in size

4.According to the text, dark matter ________.

A. could accelerate the speed of stars

B. could lessen the mass of objects in galaxies

C. makes up the entire universe and its stars

D. may help us identify the origins of the universe

Answer

1.A

2.C

3.B

4.D

【解析】

试题分析：本文讲述了暗物质的一些知识。

1. 数字计算题。根据文章第二段的句子The same object weighs only half as much on Mars as it does on Earth and almost three times as much on Jupiter.可知，地球上15 kg的物体在火星上重量只有在地球上重量的一半（7.5 kg），在木星上是地球上重量的三倍（45 kg）。故选A。

2. 细节理解题。根据第四段内容The mass of the Milky Way is only half as much as the mass of another nearby galaxy, Andromeda. This seems strange, and dark matter may explain why.可知，作者提到the Milky Way和Andromeda是为了显示研究“暗物质”有可能解决一些科学问题。故选C。

3. 细节理解题。根据最后一段We can’t see dark matter, it’s very difficult to measure and we can’t find out its mass.可知，“暗物质”很难调查是因为我们看不到“暗物质”，很难测量和查明它的质量。故B正确。

4. 推理判断题。根据文章倒数第二段Finding out more about dark matter could help us understand how the universe began可知，更多的了解“暗物质”可能帮助我们理解宇宙的形成。故D正确。

考点：考查科教类短文阅读。