重点讲解：
1. happen to do sth. 碰巧；凑巧；
例句：We happen to hold the same view.
我们两人的想法不谋而合iX~%|]jS%t=n]tCuKSFu。
2. on one's own 独立地；依靠自己地；
例句：All employees who move into supervisory positions must figure it out on their own.
所有打算竞争管理岗位的员工必须完全依靠自己完成hsNfH~8ej4。
3. first of all 第一；首先；
例句：First of all, machines had no hardware problems.
首先，机器没有硬件毛病|#h+UBME%H!V]k。
4. put to sleep 使（尤指有病或有伤的动物）无痛苦地死去；使长眠；
例句：I'm going take the dog down to the vet's and have her put to sleep.
我要把小狗带到兽医那里，让她安乐死C+L&.#eM,V。
5. fall off 脱落，掉落；
例句：Mary scrape her knee when she fall off her bike.
玛丽从脚踏车上摔下来擦伤了膝盖7[M0nJ+FCO;50。