试一试: Woman: Why weren't you at the party last night? Man: I ___ study for a test. 选出那个男人会说的话。 (had to / didn't have to / has to) 答案: had to — 他昨晚为了考试没去派对，所以他当时必须学习：had to。
didn't have to + 动词
过去没有规定、可以自己选的事，用 didn't have to + 动词。
I didn't have to go to school today.
试一试: Man: Was the form long? Woman: No. I ___ write much. Just my name and address. 选出那位女士会说的话。 (didn't have to / had to / don't have to) 答案: didn't have to — 表格上只要填名字和地址，所以她不用写很多：didn't have to。
Did you have to …?：过去是不是必须……？
问过去有没有这个规定，就说 Did you have to + 动词？
Did you have to wear a uniform at school?
Did he have to pay for the ticket?
试一试: Man: ___ get up early for the trip? Woman: Yes. The train left at six, so I got up at five. 选出那个男人会说的话。 (Did you have to / Do you have to / Did you forget to) 答案: Did you have to — 旅行已经结束了，火车的时间让她五点就得起床，所以他问 Did you have to。