water can change from one form to anotheer. the heat of the sun evaporates water from the oceans, seas, rivers and lakes. the heat also evaporates water from the ground and from plants and animals. water vapour is formed. this forms clouds in the air.
when the clouds come near a mountain, they are forced to rise. as the clouds rise, they are cooled. the higher they rise, the more they are cooled. this causes more and more water vapour to condense. in this way, the tiny drops of water in the clouds get bigger and bigger until they are heavy enough to fall to the earth as rain.
some rain water which falls on the earth is again evaporated. some of it sinks into the ground. it may be used up by thirsty plants. it may reach a well or a spring. most of the water goes back to the rivers, seas and oceans. this process then starts all over again. this process is called the water cycle.
上海市2016届高三英语一轮核心词汇复习:第17课时《palace~poison》
广州市广雅中学高考英语一轮陷阱题指导:it陷阱题
2016届高考英语一轮复习(外研版)考点规范训练:必修3 Module 4 Sandstorms in Asia
2016届高考(北师大版)英语一轮复习:第一部分模块复习方略 必修二 4
上海市2016届高三英语一轮核心词汇复习:第5课时《careless~clue》
2016届高考英语一轮复习(外研版)考点规范训练:选修6 Module 3 Interpersonal Relationships—Friendship
2016届高考英语一轮复习(外研版)考点规范训练:必修4 Module 6 Unexplained Mysteries of the Natural World
上海市2016届高三英语一轮核心词汇复习:第9课时《elegant~favor》
2016届高考英语一轮复习(外研版)考点规范训练:必修3 Module 6 Old and New
2016届高考英语一轮复习(外研版)考点规范训练:选修6 Module 5 Cloning
2016届高考英语一轮复习(外研版)考点规范训练:必修3 Module 2 Developing and Developed Countries
2016届高考英语一轮复习(外研版)考点规范训练:必修4 Module 5 A Trip Along the Three Gorges
上海市2016届高三英语一轮核心词汇复习:第2课时《amuse~average》
上海市2016届高三英语一轮核心词汇复习:第8课时《digest~electronic》
上海市2016届高三英语一轮核心词汇复习:第3课时《avoid~blood》
上海市2016届高三英语一轮核心词汇复习:第18课时《poisonous~push》
上海市2016届高三英语一轮核心词汇复习:第11课时《funeral~harvest》
2016届高考英语一轮复习(外研版)考点规范训练:必修4 Module 4 Great Scientists
2016届高考英语一轮复习(外研版)考点规范训练:必修5 Module 3 Adventure in Literature and the Cinema
上海市2016届高三英语一轮核心词汇复习:第7课时《course~dig》
上海市2016届高三英语一轮核心词汇复习:第1课时《a~amount》
上海市2016届高三英语一轮核心词汇复习:第16课时《nod~pair》
上海市2016届高三英语一轮核心词汇复习:第6课时《coach~courage》
2016届高考英语一轮复习(外研版)考点规范训练:必修5 Module 5 The Great Sports Personality
2016届高考英语一轮复习(外研版)考点规范训练:必修3 Module 5 Great People and Great Inventions of Ancient China
2016届高考英语一轮复习(外研版)考点规范训练:选修6 Module 1 Small Talk
2016届高考英语一轮复习(外研版)考点规范训练:必修4 Module 2 Traffic Jam
上海市2016届高三英语一轮核心词汇复习:General Revision2
2016届高考英语一轮复习(外研版)考点规范训练:必修3 Module 1 Europe
上海市2016届高三英语一轮核心词汇复习:第4课时《blouse~careful》
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