重点讲解：
1. in advance 提前；事先；
Because of the popularity of the region, it is advisable to book hotels or camp sites in advance.
鉴于该地区很受人们青睐，最好提前预订旅馆或宿营地_NHV%^N;Q_9Tq。
2. nail down 弄清；确定；
It would be useful if you could nail down the source of this tension.
如果你能弄清这种紧张的根源，将会大有益处[vyGy560Ul。
3. in contrast 相反；
In contrast, the lives of girls in well-to-do families were often very sheltered.
相反，生活在富裕家庭的女孩子通常都备受呵护9C^XG2u;8JxIHJrw。
4. when it comes to 谈到；涉及；
It's easy to think that individuals can't make a difference when it comes to the issue of global warming.
当说到全球变暖的问题时，人们似乎都觉得个人的力量微不足道,bxvS.O65LoopE9N9s。