一、 Don't worry. 别担心。（劝告对方别担忧）
a. — Is my illness serious? 我的病严重吗？
   — Don't worry. You'll be well soon. 别担心，你很快就会好的。
b. — Can I pass the exam? 我能通过这次考试吗？
   — Don't worry. I think you can. 别担心，我认为你能通过。

二、 Don't be afraid. 别担心。（劝告对方别担心）
a. — Will he agree to see me? 他会同意见我吗？
   — Don't be afraid. 别担心。
b. — Will the exam be very difficult? 考试会很难吗？
   — Don't be afraid. 别担心。