A:is
B:are
一个多边形的内角和是720°,这个多边形的边数是( )
完形填空
Look! There 1many kites in the2.They are red,yellow and blue.I like 3kites 4 much.But I can't fly very5.My brother Peter can do6 well.He often 7me fly kites.We go out8our kites every Sunday.9my brother's help,now I can fly10.
实验室制取H2,并用排水法收集,其正确的操作顺序是____。
①固定装置 ②加入锌粒 ③ 加入H2SO4 ④检查气密性 ⑤收集 ⑥验纯