重点讲解：
1. be in danger of
处于…危险之中；
eg. He was in danger of losing his life.
他有失去生命的危险。
eg. The economy is in danger of collapse unless far-reaching reforms are implemented.
如果不实施影响深远的改革，经济就面临崩溃的危险。
2. knock down
（被车）撞倒；
eg. A drunk driver knocked down and killed two girls.
一个酒后驾驶的司机撞死了两个女孩儿。
eg. She run to the man who have be knock down and give him first aid until the ambulance arrive .
她跑到被撞倒的男人身边对他进行急救直至救护车到来。
3. even if
即使；尽管；纵然；
eg. I wouldn't lose courage even if I should fail ten times.
即使要失败十次，我也绝不灰心。
eg. Don't let down even if the going is good.
即便在顺利的情况下也不要松劲。
