单选题 I didn't send out my application form last week, but I ______.
A. had to B. would C. must D. should have

【正确答案】 D
【答案解析】[解析] but I should have(sent out my application form)但我本应该寄出(申请表)这是省略句的一种，为避免重复，省略了前面已经提到的内容send out my application form。注意这个表示完成时态的have不能省略，省略了have就变成谈论现在而不是谈论过去的事情。