重点讲解：
1. less than
（用在数字或数量前）少于，低于，比…少；
eg. Motorways actually cover less than 0.1 percent of the countryside.
高速公路的实际覆盖面积还不到农村地区的0。1%。
eg. Less than a half hour later he returned upstairs.
不到半个小时，他又跑上楼来。
2. cling to
缠住；依附；
eg. The road extends several miles along coastline, then cling to the inland.
这条路延海岸线延伸了几英里, 然后转向内陆。
eg. I have had too many identities to cling to one name!
我有太多的身份而不能被附着于一个名字上。
3. by far
（比较时用作强调）显然，…得多，大大地；
eg. By far the most important issue for them is unemployment.
对他们来说最重要的无疑就是失业问题。
eg. It was better by far to be clear-headed.
保持头脑清醒要好得多。