7．Researchers have discovered the first Earth-sized planet．It was first marked by scientists using NASA's Kepler telescope（望远镜），so it's called Kepler-186f．It lies about 500 light years from Earth and goes around its star．The planet is the right distance from its star for water：not too close and not too far．Water is one important condition that scientists guess is necessary for life．So it could have water and possible life．It's called a true Earth cousin．
"This planet is an Earth cousin，not an Earth twin，"said Barclay，who is among a team of scientists reporting on the discovery in the magazine Science this week．
"It's very exciting to find a planet similar to the Earth，"Barclay said．"It's not easy work because things change as we get more measurements．"
"It's possible for life to live in this planet，but that doesn't mean there is life in it．"Barclay said．
So far，scientists have found nearly 1，800 planets in the universe．
"The past year has seen a lot of progress in the search for Earth-like planets．Kepler-186f is very important because it is the first planet that is the same temperature and is almost the same size as Earth，"scientist David Charbonneau wrote in an email．
48．Researchers have already found aboutCplanets now．
A.500
B.186
C.1800
D.1801
49．Which of the following about Kepler-186f is NOT true according to the passage？A
A．It could have water and possible life，so perhaps we might live there．
B．It's almost as hot as and as large as Earth．
C．In the future，scientists will study the air of it by telescope．
D．It's an Earth-like planet．
50．We can probably read this article inB．
A．a story book
B．a newspaper
C．a text book
D．a sport magazine
51．What is the best title of the passage？D
A．Space research．
B．Journey to space．
C．Is there water and possible life in Kepler-186f？
D．Scientists discover most earth-like planet．
分析 文章大意：这是一篇科普知识类阅读，短文主要介绍美国宇航局利用开普勒望远镜发现第一个地球大小的行星，所以被命名为Kepler-186f．这颗行星离它所环绕的恒星正处于合适的距离范围内，以至于行星表面有液态水存在．Kepler-186f的发现是非常重要的，因为它是第一个与地球有相同的温度和相同大小的行星．
解答 48．答案：C．细节理解题．根据倒数第二段So far，scientists have found nearly 1，800 planets in the universe．迄今为止，科学家已经在宇宙中发现了近1800颗行星．可知，选C．
49．答案：A．推理判断题．根据倒数第三段"It's possible for life to live in this planet，but that doesn't mean there is life in it．""生活在这个星球上是有可能的，但这并不意味着它有生命．"，可知，A选项"它可能有水和可能有生命，所以也许我们可以住在那里．"是不正确的．选A．
50．答案：B．题材来源题．A一本故事书．B一份报纸．C一本教科书．D一个运动杂志．根据第一句Researchers have discovered the first Earth-sized planet．研究人员发现了第一颗地球大小的行星．可知，应该来源于一份报纸．选B．
51．答案：D．主旨大意题．根据最后一段The past year has seen a lot of progress in the search for Earth-like planets过去一年在寻找地球类行星方面取得了很大进展．可知，短文主要介绍科学家发现大多数地球类行星．选D．
点评 阅读题型，要注重句子与句子之间、段落与段落之间逻辑关系以及对篇章的整体理解．根据所给问题选择正确选项完成试题．
