重点讲解：
1. get to the bottom of 找到…的真正起因；查寻到…的根；
例句：She got suspicious and decided to get to the bottom of it.
她起了疑惑，便决定弄个水落石出c*oileJ7&byIfcf!eh。
2. all of a sudden 突然地；出乎意料地；
例句：All of a sudden there was a terrific bang and a flash of smoke.
突然传来惊天动地一声响，还冒出一股烟Vh2us|=O,x1&8TLk。
3. keep up 保持；
例句：There will be a major incentive among TV channels to keep standards up.
将会有重大举措鼓励各电视频道维持高标准nWCLbh=[b2toJiq。
4. in the first place 起初；一开始；
例句：It was a shooting star that propelled me into astronomy in the first place.
最初是一颗流星促使我从事天文学2dNrv;k2o1VoUIE_|mD。