单选题 I' m not surprised you failed the exam. You ______ have worked harder.
A. should B. must C. would D. ought

【正确答案】 A
【答案解析】[解析] 句法结构题。你考试不及格我一点都不惊讶，你本应该更用功些。should have done表达应该做而没做。