长和宽都不相同的两个长方形，周长一定不相等。[ ]
错误
用单词的适当形式填空。
1.Mr. Smith is ________(sit) on the couch.
2.I ________(buy)some Christmas cards yesterday.
3.Li Ming is ________(write) a letter.
4.We are going to ________(make) a snowman.
5.Danny has a pair of ________(skate) for Li Ming.
简述吸痰术.
