Question

【題目】On a clear night, you can see a sky paced with stars. But you can’t see planets orbiting any of these stars, even with the strongest Earth—based telescopes. Astronomers reported that they discovered seven Earth—sized planets orbiting a nearby star called TRAPPIST – 1 in February. They had to rely on indirect evidence to tell them that the planets are there. By doing some math, they figured out the number of planets and the distance of their orbits.

TRAPPIST – 1 is a red dwarf （紅矮星）, much smaller than our sun, but larger than Jupiter (木星). If the sun were the size of a basketball, TRAPPIST – 1would be the size of a gold ball. This star is one of our closest neighbors, just like the moon to the earth in space.

When astronomers using Earth-based telescopes to study TRAPPIST – 1,they noticed that every once in a while, it became slightly dim（昏暗）. They decided that a planet must be passing in front of the star, blocking part of the light. This dimming would come and go as the planet orbited the star, passing alternately (交替地) behind and in front of the star regularly.

By making careful observations, astronomers expected to get a rough idea of the planet’s size from the pattern of dimming light. But the light level changed often and not at evenly spaced (均勻間隔的) times. The astronomers had to conclude they were looking at more than one planet! To get additional data, NASA’s spritzer Space Telescope measured TRAPPIST –1’s brightness nearly continuously for 20 days, catching 34 crossings of planets in front of the star. Sorting through the mess of data, the astronomers found that the innermost planet completes its orbit in 1.5 Earth days, while the outermost planet takes 20 days. Once you know how long it takes each planet to complete an orbit, you can work out how far it is from the star compared with the other planets.

The TRAPPIST – 1 planets are not alone. So far, astronomers have found more than 3,400 planets that orbit other stars.

【1】How did astronomers know the number of planets orbiting TRAPPIST –1?

A. They used their eyes. B. They used telescopes.

C. They performed some calculation. D. They made some guess.

【2】How does the author introduce TRAPPIST – 1 in paragraph 2?

A. By giving examples. B. By making comparisons.

C. By providing research results. D. By listing some numbers.

【3】What probably causes the star TRAPPIST – 1 to be slightly dim?

A. The telescope’s failure. B. The cloud floating around.

C. The star’s moving. D. The passing planets.

【4】What’s the main idea of Paragraph 4?

A. The ways to get the information of the planets.

B. The introduction of the planets.

C. The distances of the planets to the star.

D. The astronomers’ effort of exploring TRAPPIST – 1.

Answer 1

【答案】

【1】C

【2】B

【3】D

【4】A

【解析】這是一篇說明文。本文主要介紹了天文學(xué)家發(fā)現(xiàn)的一顆恒星-TRAPPIST - 1。這是一個(gè)紅矮星，比太陽小，木星大，是離我們最近的鄰居之一。

【1】細(xì)節(jié)理解題。由文中第一段的By doing some math, they figured out the number of planets and the distance of their orbits.可知，天文學(xué)家們通過一些數(shù)學(xué)計(jì)算，統(tǒng)計(jì)出了行星的數(shù)量。故C選項(xiàng)正確。

【2】推理判斷題。由第二段的If the sun were the size of a basketball, TRAPPIST – 1would be the size of a gold ball. 可知，作者把太陽比做籃球，把TRAPPIST – 1比做金球來告訴讀者它的體重，所以這里用的是作比較的方法。故B選項(xiàng)正確。

【3】推理判斷題。由文中第三段的 planet must be passing in front of the star, blocking part of the light. This dimming would come and go as the planet orbited the star, passing alternately (交替地) behind and in front of the star regularly.可知，當(dāng)行星經(jīng)過恒星時(shí)就會阻擋一些光線，也就是說經(jīng)過的行星引起了TRAPPIST – 1 輕微的昏暗。D選項(xiàng)正確。

【4】段落大意題。根據(jù)文中第四段的astronomers expected to get a rough idea of the planet’s size from the pattern of dimming light. ，To get additional data,Sorting through the mess of data,可知，該段主要講的是天文學(xué)家如何更多的獲得行星的一些信息，也就是獲取行星信息的一些方式。故A選項(xiàng)正確。