A:中和反应生成盐和水,所以生成盐和水的反应都是中和反应
B:盐是由金属离子和酸根离子组成的,所以盐中一定含有金属离子
C:向某固体物质中加入稀盐酸,生成无色无味气体,证明该物质一定是碳酸盐
D:碱性溶液能使酚酞试液变红色,所以能使酚酞试液变红色的溶液的pH一定大于7
边长为1的正六边形的外接圆半径是____ .
已知a、b∈R,a>b>e(其中e是自然对数的底数),求证:ba>ab.(提示:可考虑用分析法找思路)
①I'd like to go with you, ____ I'm too busy.
②It was only five minutes'walk from here, ____ we didn't take a taxi.
③ Suddenly he tripped____fell.____ he woke up.
④You can go on foot, ____ you like.It's not far.
⑤I fell off my bike last Saturday,____ hurt my foot.