1. 债务;欠款
    A debt is a sum of money that you owe someone.

    e.g. Three years later, he is still paying off his debts...
           都3年了，他仍在偿还债务。
    e.g. Shrinking economies mean falling tax revenues and more government debt.
           经济收缩意味着税收的减少和政府债务的增加。

2. 负债（状态）
    Debt is the state of owing money.

    e.g. Stress is a main reason for debt.
           重压是负债的一个主要原因。

3. (表示感激）我欠你个人情/我受你的恩惠
    You use debt in expressions such as I owe you a debt or I am in your debt when you are expressing gratitude for something that someone has done for you.

    e.g. He was so good to me that I can never repay the debt I owe him...
           他对我太好了，我永远也还不清这份人情。
    e.g. I owe a debt of thanks to Joyce Thompson, whose careful and able research was of great help...
           我要衷心地感谢乔伊斯·汤普森先生，他严谨而卓著的研究给予了我极大的帮助。