选出合适的应答语。
A. You should go to bed early.
B. You should wear a sweater.
C. She should tell the teacher and go to see the doctor.
D. You should tell your mother.
E. You should take it to see the vet.
F. You should help her do some chores.
下列属于我国必须坚持的发展战略是（）①可持续发展 ②计划生育 ③节约资源 ④环境保护 ⑤人才强国 ⑥科教兴国
边长为1的正六边形的外接圆半径是____ ．
缺水已是一个世界性问题，因此我们要珍惜每一滴水．一些严重缺水的国家，露水也是重要的水资源，露水的形成属于物态变化中的（ ）
