Learn 3 particles to express tense.(了, 着, 过)

As we know, Chinese language doesn't have tense like English, but it has some words indicate the status. Such as 了,着,过, they are particles.

1. 了 usually indicates completion.

他吃了一个苹果

He has had an apple.

2. 着 often indicates things ongoing.

他正吃着一个苹果

He is eating an apple.

3. 过 usually means things ever existed.

他今天吃过一个苹果

He ate an apple today.