重点讲解：
1. so far 迄今为止；到目前为止；
His whereabouts have been utterly unknown so far.
迄今他的下落全然未知。
2. beef up 改善；加强；改进；提高；
I want to beef up my skill.
我想要加强我的技巧。
3. in other words 换言之；换句话说；也就是说；
A common saying goes, "Knit the brows and you will hit upon a stratagem." In other words, much thinking yields wisdom.
俗话说：“眉头一皱，计上心来”。就是说多想出智慧。
4. all at once 同时；一起；
A number of things happened all at once.
几件事一起发生了。