How to use 'when'?
Recently, I read a sentence on Italki.

'I knew him when he worked in China about five years ago.' Is this sentence okay? I want to use only 'when' or while' in this sentence. Please give me answer.

Question

How to use 'when'?
Recently, I read a sentence on Italki.

'I knew him when he worked in China about five years ago.' Is this sentence okay? I want to use only 'when' or while' in this sentence. Please give me answer.

Answer

I knew him when he worked in China. ( preterite )( definite past )

I knew him while he was working in China. ( past progressive )