You and I are in the same situation. I also got two B's in college, but I didn't care much at that time. As a result, I found that I was not fully prepared at that time, and now I just want to cry. Anyway, I am preparing for the exam with Chang Yan Mandarin APP, and I feel that its various functions are quite professional and its resources are relatively rich. It's really hard to find dry goods on the Internet, such as the outline of Putonghua exam, the analysis of propositional speech ideas, the reference outline, customs clearance cheats, and the analysis of phonetic change rules. However, Chang Yan Putonghua APP can be downloaded for free, and its online learning and practice covers all the questions of Putonghua exam, from "phonological practice" to "monosyllabic". Moreover, there are hundreds of national testers on the Mandarin APP who provide online live courses such as "one-on-one live class, small class for 4-6 people, theme recording and broadcasting class, and training camp". Integral and skill are very valuable. Please prepare when you have time. I hope we can all take the second grade exam.