重点讲解：
1. at least （数量）至少，不少于；
例句：Officials did not release exact figures for the contract but the project is estimated to be worth at least five-point-three billion dollars.
有关官员没有公布协议的具体数字，但是估计这一项目价值至少53亿美元2+wu_nSgnqO5-;GD。
2. why not (表示建议)为什么(不)；
例句：Why not give Claire a call?
为什么不给克莱尔打个电话？
3. derive from （使）起源于；（使）来自；
例句：Anna's strength is derived from her parents and her sisters.
安娜的坚强源自于她的父母和姐姐们T#5t1Z*-@~j(HHa。
4. help to do sth. 帮助；帮忙；
例句：He has helped to raise a lot of money.
他帮着筹集了很多钱OD1eJ4cqt)0。