重点讲解：
1. used to do sth.
过去常常；过去曾做某事；
eg. We used to be good friends, but fell apart about a year ago.
我们过去曾经是好朋友，但一年前关系破裂了CD48SPSB,lG6。
eg. John used to visit his parents once a week when he worked as an assistant in the city.
约翰在城里当服务员的时候，总是每周去看望父母一次^OHa0=dGQRbD。
2. stay up
深夜不睡；熬夜；
eg. People often do not sleep on the last day of year and stay up to welcome the new year. We call it pernoctating.
守岁，就是在旧年的最后一天夜里不睡觉，熬夜迎接新一年的到来ta*n[)Fy&~%ZL-y。
eg. I hope you will not always stay up late, but form a good habit of early to bed, early to rise.
我希望你不要总是熬夜，要养成早睡早起的好习惯@-B_9Brsyguc)zq0。
3. one by one
逐个地；依次地；
eg. Researchers, sometimes working more or less in teams, divide problems into small pieces and try out different solutions to them one by one.
有时候，研究人员或多或少地分组合作，把问题分解并且逐个找到相应的解决办法8+PKp#Fq=Ojrb。
eg. All the applicants were interviewed one by one.
所有的申请者一个接着一个参加面试1;AL0kAbs%We!~O)Fs9!。