Mars is extremely cold even in summer,and the streaks are in places where the temperature is as low as minus 10 degrees Fahrenheit.But salt can lower the freezing point of water and melt ice.

　　The source (源头) of the water is a mystery.Scientists noted it could be melting ice.It could be an underground aquifer,which is rock or sand that can hold water.It is possibly water vapor from the thin Martian atmosphere,or it may be a combination.Michael Meyer,lead scientist for NASA’s Mars exploration program,said the only definitive way for now to determine whether there’s life on Mars is to collect rocks and soil for analysis on Earth—something a U.S.lander set for lift-off in 2020 will do.

　　1.What would be the best title for the text?

　　A.Streams of Water Spotted on Mars

　　B.Astronauts Will Land on Mars

　　C.NASA’s Mars Exploration Program

　　D.A Breakthrough in the Exploration of Mars

　　2.According to John Grunsfeld,there seems to be　 on Mars. 

　　A.salty waterB.standing water

　　C.rocket fuel D.human beings

　　3.Scientists are uncertain about the 　of the water on Mars. 

　　A.state B.source

　　C.temperature D.taste

　　4.What matters to the existence of liquid water on Mars?

　　A.The distance from the sun.

　　B.The favorable climate.

【2017届高考英语一轮复习考点规范练：20 选修7 Unit 20（北师大版含解析）】相关文章：

★ 2014高考英语（新人教版）一轮基础训练（20）A、B卷（附答案或解析）

★ 湖南省汝城二中2014届高考英语一轮复习阅读训练 (65)

★ 【三维设计】2017届高考英语（江苏专用）二轮复习阅读理解解题技法示范课件：4

★ 【课堂新坐标】2017届高考英语（通用版）二轮复习短文改错专题训练：训练1 短文改错（Ⅰ）（含解析）

★ 【北师大版】2014届高考英语一轮复习指导课时作业：Unit 8 A卷 Word版含解析

★ 【三维设计】2017版（江苏专用）二轮复习练习：选修8 Unit 4《Films and film events》单元检测（含解析）

★ 2017届高考英语二轮复习课时训练：22（含解析）

★ 湖南省汝城二中2014届高考英语一轮复习阅读训练 (54)

★ 2017届高考英语二轮复习课时训练：2（含解析）

★ 【浙江专用】2014届高考英语一轮复习课时作业(二十六)选修6Unit 1《Art》