长方形面积是3a2-3ab+6a，一边长为3a，则它周长是（ ）。
8a-2b+4
用所给单词的适当形式填空。
①The _____ (girl) name is Mary.
②I have a _____ (sister的对应词) . His name is Li Ming.
③Here _____ (be) my family photos.
④Mary and I _____ (be) good friends.
不能若是，而欲生之，曾不可以告咳婴之儿。______
