首页
登录
职称英语
What is the main topic of the passage? [br] [originaltext] What makes it ra
What is the main topic of the passage? [br] [originaltext] What makes it ra
游客
2024-10-16
20
管理
问题
What is the main topic of the passage? [br]
What makes it rain.9 Rain falls from clouds for the same reason anything falls to Earth. The Earth’s gravity pulls it. But every cloud is made of water droplets or ice crystals. Why doesn’t rain or snow fall constantly from all clouds? The droplets or ice crystals in clouds are exceedingly small. The effect of gravity on them is minute. Air currents move and lift droplets so that the net downward displacement is zero, even though the droplets are in constant motion.
Droplets and ice crystals behave somewhat like dust in the air made visible in a shaft of sunlight. To the casual observer, dust seems to act in a totally random fashion, moving about chaotically without fixed direction. But in fact dust particles are much larger than water droplets and they finally fall. The cloud droplet of average size is only 1/2500 inch in diameter. It is so small that it would take sixteen hours to fall a mile in perfectly still air, and it does not fall out of moving air at all. Only when the droplet grows to a diameter of 1/125 inch or larger can it fall from the cloud. The average raindrop contains a million times as much water as a tiny cloud droplet. The growth of a cloud droplet to a size large enough to fall out is the cause of rain and other forms of precipitation. This important growth process is called "coalescence".
选项
A、The gathering of small clouds to form large clouds.
B、The growth of droplets.
C、The fall of raindrops and other precipitation.
D、The movement of dust particles in the sunlight.
答案
B
解析
转载请注明原文地址:https://tihaiku.com/zcyy/3803417.html
相关试题推荐
WhowasJohnMills?[br][originaltext]TheBritishactorJohnMillshasdie
WhowasJohnMills?[originaltext]TheBritishactorJohnMillshasdiedatt
Whatisthemaintopicofthepassage?[originaltext]Whatmakesitrain.9R
Accordingtothepassage,theworkof"YouthSummit"refersto[br][originalte
Accordingtothepassage,theworkof"YouthSummit"refersto[br][originalte
Accordingtothepassage,theworkof"YouthSummit"refersto[originaltext]
Beforereturningtohisoffice,Joehasto[br][originaltext]M:Ihavetochan
Beforereturningtohisoffice,Joehasto[originaltext]M:Ihavetochangeah
Whatarethespeakerstalkingabout?[br][originaltext]W:Excuseme,DrChandl
Londontaxidriversarcveryefficient______[br][originaltext]Londontaxi
随机试题
TheChacoPhenomenonP1:Betweenabout900to1150AD,amysteriousStoneAgecu
Worse,thoughChinatookanearlydecisionto______(吸引制造业方面的国外直接投资),ithasb
Crimeisincreasingworldwide.Thereiseveryreasontobelievethe【B1】_____
中国结(Chineseknot)是中国特有的传统民间手工编织艺术,体现着中国人的智慧和深厚文化。作为独特的中华文化的代表,中国结极易被外国人辨认出来。
流体流过节流孔板时,流束在孔板的哪个区域收缩到最小?()A.进口处 B.进
回弹法检测一般构件的混凝土强度,要求的测区数量不宜少于()。A.5个 B.1
商品流通的过程就是()。A:商品价值形态的转化过程 B:创造空间和时间价值的过
按照迁移内容的抽象与概括化水平,可以把学习迁移分为( )。A、水平迁移与垂直迁
统计学是关于()的学科。A.收集、整理和描述数据 B.利用样本信息验证总体假
(2013年真题)2012年12月31日,企业某项固定资产的公允价值为
最新回复
(
0
)