Buy a green card of Peking University! I have been working on the green card of Peking University for several years, and there are explanations and text introductions beside it, which are good for understanding the text. In addition, I have been writing the green card of Peking University and Dianzhong recently. I was right. The questions in these two workbooks are similar, not difficult, but common and often tested! Personally, I prefer the green card of Peking University. Choose for yourself. It's best not to buy too many exercises, which will also increase your burden. It is best to choose a workbook such as Peking University Green Card, which has a good topic! !