搜题请搜索小程序“爱下问搜题”
问题 填空题

如图是乙烯在氧气中燃烧的微观示意图．

分析图示信息，回答下列问题：

（1）如图共有______种分子，B分子是由______构成；

（2）写出该反应的化学方程式______．

答案

（1）A图表示由2个C原子和4个H原子构成的一个分子；B图表示三个由2个O原子构成的分子，三个分子构成相同为同种分子；C图表示两个由1个O原子与2个H原子构成的分子，两个分子构成相同为同种分子；D图表示两个由1个C原子与2个O原子构成的分子，丙个分子构成相同为同种分子；因此，共有4种分子；B分子由氧原子构成；

（2）根据分子的构成，物质A可表示为CH4，物质B表示为O2，物质C表示为H2O，物质D表示为CO2；则该反应的化学方程式为C2H4+3O2

 点燃 
.
 
2H2O+2CO2；

故答案为：（1）4；氧原子（或O原子）；

（2）C2H4+3O2

 点燃 
.
 
2H2O+2CO2．

完形填空

基础训练篇（17）

In order to know a foreign language thoroughly, four things are necessary. Firstly, we must understand the language when we hear    1.           spoken. Secondly, we must be able to speak it ourselves correctly with confidence and without hesitation.    2.                , we must be able to read the language, and fourthly, we must be able to write it. We must be able to make sentences that are grammatically correct.

There is no easy way to success   3.            language learning.          4.                   good memory is a great help, but it is not enough only    5.                   (memorize) rules from a grammar book. It is not much use learning by heart long lists of words and   6.             meanings, studying the dictionary and so on. We must learn by using the language. 7.               we are satisfied with only a few rules we have memorized, we are not really learning the language. “Learn through use” is a good piece of   8.            (advise) for those   9.           are studying a new language. Practice is important. We must practise speaking and   10.            (write) the language whenever we can.
查看答案
单项选择题

主张根据社会需要来制定高校培养目标的是（）。

A.个人本位论

B.马克思主义关于人的全面发展学说

C.社会本位论

D.政治统帅论
查看答案