boys in their teens   少男；十三到十九岁的男孩
　　put an end to v. stop sth. happening  结束；终止
　　Let's put an end to smoking.  让我们停止吸烟吧！
　　operation            n.[c] the act of a surgeon who cuts the body of a patient（外科）手术
　　He has to have an operation to undergo at once.  他不得不马上动手术。
　　n.[u] working, the way something works  工作；运转
　　The machine came into operation.   机器开始运转了。
　　knock down  strike to the ground with a blow, etc; shoot down  击倒；撞倒
　　I was almost knocked down by a motorcar.   我差点被一辆汽车撞倒。
　　level                n. surface parallel with horizon; such a surface with reference to its height  平面；水平面
　　The river level rose after the rain.  雨后河里的水面升高了。
　　n. how high something is  高度；级别；水平
　　We are working hard to catch up with the advanced world levels.
　　我们正在努力工作，以赶上世界先进水平。
　　junior               adj. the younger; of lower rank or position年少的；等级较低的
　　He is three years junior to me.   他比我小三岁。
　　After graduation from a junior middle school, he entered a senior middle school.
　　他初中毕业后进入高中。
　　n. a younger person  年少者；晚辈
　　She is my junior by seven years.   她比我小七岁。
　　I am his junior in life.   我是她的晚辈。
　　senior              adj. older  年长的
　　I am five years senior to him.   我比他大五岁。
　　adj. more advanced in education  较高年级的
　　He studies in a senior middle school.   他念高中。
　　n. an older person  年长者
　　Paul is my senior by two years.   保罗长我两岁。
　　n. a person of longer service, higher rank  上司；前辈
　　He was my senior.   他过去是我的上级。
　　ie  [,aI`i:] (=that is to say, in other words) 也就是
　　option            n.[u]  right or power of choosing  选择权；选择
　　You must do it; you have no option.   你必须做这件事，你没有选择的余地。
　　n.[c] thing that is or may be chosen  选择物
　　None of the options is satisfactory.  所选之物无一令人满意。
　　broaden           v. to make or become broad or broader.（使）变宽，（使）扩大
　　For college students to do a part-time job will broaden their outlook.
　　打工使大学生开阔了眼界。
　　fall behind  not keep up; be left as in a race  赶不上；落后liuxuepaper.com