本单元的学习任务：
四会要求 （会读、会写、理解中文意思以及会自己造句然后翻译）
（一）单词：
scold, lifetime, challenge, failure, mistake, graduate, forever, encourage, guide, teenage, tear, upset, fragile, forgive, seed, graduation, program, board, balloon, decorate
（二）短语：
1) decorate the classroom with the balloon
2) think of programs for the party
3) reading the graduation album
