Cách sử dụng
The expression "in vain" means that you have tried something but it didn't work or produce the desired result. It can be used to describe a situation where your efforts have been wasted or unsuccessful. For example, "I searched for my lost keys in vain" means that you looked for your keys but couldn't find them. Another example is "I tried to convince my friend to apologize, but it was in vain" meaning trying to make your friend apologize was unsuccessful. "In vain" is usually used to express disappointment or frustration when something has not worked out as you had hoped.