Review

### 开始期末复习

听之前上过课的人说考试核心在于记忆概念，三天半的时间进行突击复习。关键在于背诵

- [x] 1-Introduction
- [x] 2-Network Effect
- [x] 3-Platform Pricing
- [x] 4-Platform Competition
- [x] 5-Platform Launch
- [x] 6-Online Reputation
- [x] 7-Position Auction
- [x] 8-Recommender System
- [x] 9-Sharing Economy