已知:Ⅰ.RCHO+R′CH2CHO →Δ稀氢氧化钠 +H2O(R、R′表示烃基或氢)
Ⅱ.醛与二元醇(如:乙二醇)可生成环状缩醛:
喜、怒、哀、乐是人类情绪的四种基本形式。( )
中国信息产业网2011年12月21日讯 入世10年来,中国成为经济全球化和区域经济一体化的参与者、推动者和受益者,对外贸易和经济都取得了迅猛发展.商务部部长陈德铭此前表示,未来十年,中国将坚持更加积极主动的开放战略,更加积极主动地参与经济全球化,实现互利共赢
下列关于中国在世界上的地位的叙述,正确的是( )
名著阅读。
The Internet has become part of teenage life. There’s a report on 3,375 students aged from 10 to 18 in seven Chinese cities. It says that 38% of them believe they use the Internet often. While most of them get useful information and use the Internet to help in their studies, some are not using it in a good way. Many are playing online games too much. A few even visit Web sites they should not look at. Bad things can happen if young people spend too much time on the Internet. In order to help young people use the Internet in a good way, a textbook on good Internet behavior has started to be used in some Shanghai middle schools this term. It uses real examples to teach students all about good ways of using the Internet. Some students also make online friends. But if you are meeting a friend offline, let your parents know. Teachers and parents all think the book is a very good idea. It will teach students how to be a good person in the online world. It will be a guide for teens using the Internet and keep students away from bad sites.
在△ABC中,∠A,∠B,∠C的对边分别为a,b,c,且(a+b)(a﹣b)=c2,则( )