否定句: You oughtn’t to have done that. 那件事你實在不該做的。(一般用法,過去非事實語氣) 2. have to: 必須 You have to tell your father.你必須告訴你父親。(一般用法) That has to be the pizza man at the door. 門口來的一定是送披薩的。(猜現在) 疑問句: Do you have to leave now?