推理是一种重要的化学思维方法,以下推理合理的是( )
A:酸碱发生中和反应生成盐和水,所以生成盐和水的反应一定是中和反应
B:酸溶液中都含有氢离子,所以含有氢元素的物质一定是酸
C:有机物都含有碳元素,所以含有碳元素的化合物一定是有机物
D:化合物是由不同元素组成的纯净物,所以只含一种元素的物质一定不是化合物
《乡村教师支持计划(2015—2020年)》指出:“必须把乡村教师队伍建设摆在优先发展的战略地位;到2020年,努力造就一支素质优良、甘于奉献、扎根乡村的教师队伍。”这说明( )
①发展教育是先进文化的重要内容 ②教育是民族振兴和社会进步的基石
③教育是综合国力竞争的决定性因素 ④我国的发展离不开教育的进步
阅读下面短文,从短文后所给的A、B、C、D四个选项中选出能填入相应空白处的最佳选项。
This is an apple tree. There are many 1 on the tree. There are some 2under it, too. They are 3 happily. Under the tree I can 4 a boy and a girl. They're playing games with the dogs. The boy is 5 a blue sweater and white shoes. He is Jim. He is 6 American student. He is 14. He 7 his school very much. The girl is Jim's sister, 8 name is Cindy. She is 11. She is in a yellow dress. Her shoes are yellow. 9 . Now they are standing here, they are waiting for their friends. They 10 to play games under the tree.
下列关于人体内环境稳态调节的叙述错误的是 ( )