随机 40 题，检验你的整体脉络40 random questions to test the whole map

从 120 道题中随机抽取 40 道，限时 30 分钟。交卷后显示得分、逐题解析，并把错题写入错题本。40 questions are drawn from 120, with a 30-minute limit. After submitting you get a score, per-question explanations and wrong answers saved to the wrong-answer book.