单选题 Why is ______ you are not well prepared for the class?
A. it B. that C. that it D. it that

【正确答案】 D
【答案解析】[解析] 根据结构可以看出这里是一个强调句型，被强调成分为疑问副词why，例如：Why is it that he failed again?到底为什么他又失败了?由此可见D为正确答案。