重点讲解：
1. part of 一些；部分；
Part of the roof has caved in.
屋顶有一部分塌了下来P*om*XP*lUk^J22jf55V。
2. bring down 降（价）；
We aim to bring down prices on all our computers.
我们打算降低我们所有计算机的价格rajR6^,mTIl。
3. go missing 失踪；
Children often go missing in places of high population density, such as shopping malls, railway stations and amusement parks.
儿童容易在购物商场、火车站和游乐园等人口密度高的场所走失J&#UW5XaB..4@w%^J--。
4. be willing to do sth. 乐意的；愿意的；
I am willing to admit that I do make mistakes.
我愿意承认我确实会犯错iUkNgSzoJstCf]#]。