比一比,再组词。
胀____ 沾____ 掠____ 凑____
涨____ 站____ 谅____ 奏____
等差数列an的前n项和为Sn,若a3+a7+a11=12,则S13等于( )
Kate isn't happy because she lost her pet. Let's go to cheer her up.