be bound to

例句：

1. 1. We are bound to meet at the airport tomorrow.
   我们明天必须在机场见面。
2. 2. He was bound to fail the exam because he didn't study enough.
   他注定要失败这次考试，因为他没有足够地学习。
3. 3. The weather is bound to change before nightfall.
   天气在天黑之前肯定会变。