下列气体中约占空气总体积的1/5的是A.氮气B.氧气C.二氧化碳D.

下列气体中约占空气总体积的1/5的是
A.氮气B.氧气C.二氧化碳D.稀有气体

答案

B解析:

相关题目

根据句意选择正确的单词填空。 1.The plane landed on the airport__
根据句意选择正确的单词填空。 1.The plane landed on the airport_________(safe,safely). 2.Don’t you think we need time and_________(free,freedom)to relax. 3.Don’t
   There is one thing that everyone wants more than anything else.___22. They
   There is one thing that everyone wants more than anything else.___22. They think that when they have enough money to buy such things as houses,farms,and cars,they will have the thing tha
下列计算中,运算正确的是( ) A.(a﹣b)(a﹣b)=a2﹣b2
下列计算中,运算正确的是( ) A.(a﹣b)(a﹣b)=a2﹣b2              B.(x+2)(x﹣2)=x2﹣2 C.(2x+1)(2x﹣1)=2x2﹣1         D.(﹣3x+
(09学军中学第七次月考)某DNA分子中含有1000个碱基对(P元
(09学军中学第七次月考)某DNA分子中含有1000个碱基对(P元素只含32P)。若将DNA分子放在只含31P的脱氧核苷酸的培养液中让其复制3次,则子代DNA的相对
将下列这段话的第一句,改成对偶句。 名誉一定要争取,尊
将下列这段话的第一句,改成对偶句。 名誉一定要争取,尊严当然不能丧失。没有名誉就是默默无闻,这只是一种消极现象。但,丧失了尊严,就是羞
短文改错(共10小题,满分10分 I was walking home from school while sudd
短文改错(共10小题,满分10分 I was walking home from school while suddenly                  86. ______________ it rained heavy. What should I do? I didn’t have an     
刺猬遇到敌害时身体缩成一团,以背部的硬刺保护自己。但
刺猬遇到敌害时身体缩成一团,以背部的硬刺保护自己。但狐狸有时会把刺猖抛向空中,待其落地伸展躯体的刹那间,咬住其无刺的腹部而将它吃掉。
         , the mountain climbers eventually conquered Mountain Qomolangm
         , the mountain climbers eventually conquered Mountain Qomolangma.  A. As the difficulty was great        B. Great as the difficulty was  C. A great difficulty as it was   

最新题目