四年级小学生作文辅导

甲烷和氧气的混合物,其平均相对分子质量为24,则该混合气体中甲烷的质量分数为?　A.25% B.33.3% C.50% D.66.67% 相同条件下甲烷和氧气的混合气体平均相对分子质量是24,则两种气体体积的百分含量各是多少?体积比,分子个数比,质量比都是多少啊. 玻璃钢可燃吗?它的主要组成材料有哪些? 哪些东西是玻璃钢做的 玻璃钢是不是纯净物 在三相四线制电路中,如果其中一项出现短路或开路,电路将会发生什么现象,是否影响 中国现在是什么季节 玻璃钢管道用于酸性介质可不可以啊? 圆柱形玻璃钢和圆锥行玻璃钢等高等底,已经往圆柱形玻璃钢里倒入6杯水,圆锥形的玻璃钢倒入多少杯 古文的译文整篇文章翻译就可以了,请帮个忙,谢谢了! 《宣王好射》文言文中“而终身以为用九石,岂不悲哉?快 求宣王好射,文言文阅读答案 last but not least,before making the final decision ,make sure that the piace where接上you'll stay are safe.it should provide enough staff to look after the safety of their guests it's a good idea to call the hotles to ask them about their hotel sa Mr Per stood at the bus-stop and watched the cars go by,中文?句尾为什么用go by? mr.perkin stood at the bus shop and w_____the cars go by.many of the cars were new bea400s,andmost of them were yellow.mr.perkin always___same clothes as other men,ate the same food as other people,and did the same things ajter work,and at the end of 人造石基本成份有那些? 不能拆的抱枕怎么洗RT拿洗衣店挺麻烦的.还得花钱~~~ 直接洗的话 里面的东西会受损~~~ 哎~~~~ 根据汉语意思完成句子.1.最后,我们决定骑自行车去长城.At last,we made a decision to___ ___the1.最后,我们决定骑自行车去长城.At last,we made a decision to___ ___the Great Wall. 人造石英石板配方 英语翻译But it is an awkward truth that when most U.S senators were asked informally in 2000 if they would support the Kyoto Protocol should President George W.Bush send it to the Scant for ratification,the overwhelming majority,Democrats as well 求史上最难划分句子成分的语句越难越好 仓库的主要类型有哪些其功能是什么? 中国湖北省襄樊市樊城区（postcode：441000）大庆东路艺苑新村 XXX收 翻译成英文地址 美犹如盛夏的水果,是容易腐烂而难保持的.这其中美指的是什么?这句话阐明了什么道理? 富士康工程师名不副实什么意思? 名不副实 副的意思 不免名不副实是什么意思? 名不副实的名什么意思 名不副实的副是什么意思 CJ是什么啊?还有YY是what呢?前者源于“CJ的45度角仰望天空”... YY里总说的 纠结 QWQ应该是表情吧.CJ?