be under an obligation to sb.

例句：

1. 1. He is under an obligation to pay back the money he borrowed from the bank.
   他负有偿还他从银行借的钱的义务。
2. 2. She was under an obligation to attend the meeting, so she went even though she was sick.
   她有义务参加会议，尽管她生病了，所以她还是去了。
3. 3. The company has an obligation to provide safe working conditions for its employees.
   公司有义务为其员工提供安全的工作环境。