HAD

例句：

1. 1. I had to go to the store and buy some milk.
   我不得不去商店买些牛奶。
2. 2. She had a lot of work to do before the deadline.
   她有很多工作要做，在截止日期之前。
3. 3. He had to wait for his turn in line.
   他不得不排队轮到他。