– 过is used to indicate the action was done or experienced in the past.
Subject + Verb + 过 + (Object)
我见过他。(Wǒ jiàn ɡuò tā.) I met him.
我吃过。(Wǒ chī ɡuò.) I ate before.
– The negative form uses “没（有）”.
Subject + 没（有）+ Verb + 过 + (Object)
我没（有）去过日本。(Wǒ méiyǒu qù ɡuò Rìběn.) I have never been to Japan.
我没（有）听过。(Wǒ méiyǒu tīnɡ ɡuò.) I haven’t heard of it.
– The Interrogative Form：
Subject + Verb + 过+ (Object) + 吗？
你见过他吗？(Nǐ jiàn ɡuò tā mɑ?) Have you met him?
你吃过吗？(Nǐ chī ɡuò mɑ?) Have you eaten?
– Affirmative and Negative question：
Subject + Verb + 过 + (Object) + 没（有）？
你看过这部电影没（有）？(Nǐ kàn ɡuò zhè bù diànyǐnɡ méiyǒu?) Have you seen this movie？
你去过中国没（有）？(Nǐ qù ɡuò Zhōnɡɡuó méiyǒu?) Have you been to China？
Modal/aspect particle indicates that a previous situation has now been changed or some event or action took place.
– As a modal particle, “了” is used at the end of a sentence to indicate something has already happened or a previous situation has now been changed.
他去学校了。（Tā qù xuéxiào le.）He went to school.
我们结婚一年了。（Wǒmen jiéhūn yī nián le.）We got married for 1 year.
我和他去看电影了。（Wǒ hé tā qù kàn diànyǐng le.）He and I went to watch movie.
– As a dynamic auxiliary, “了” is used after verbs to refer to the completion of an action. It`s often followed by quantifiers.
去年我看了10本书。（Qùnián wǒ kànle 10 běn shū.）I read 10 books last year.
我买了很多衣服。（Wǒ mǎile hěnduō yīfu.）I bought lots of clothes.
我吃了午饭。（Wǒ chīle wǔfàn.）I have had lunch.
The two particles “过” and “了” might seem quite similar: both can be used to talk about completed actions. The differences are:
– “了” indicates that the event took place
昨天我去故宫了。(Zuótiān wǒ qù gùgōngle.) I went to the Forbidden City yesterday.
上个星期我们就认识了。(Shàng gè xīngqī wǒmen jiù rènshi le.) We met last week.
– “了” placed after a verb denotes that the action is accomplished
我买了一本汉语书。(Wǒ mǎile yī běn hànyǔ shū.) I bought a Chinese book.
我到了北京就给你打电话。(Wǒ dàole běijīng jiù gěi nǐ dǎ diànhuà. ) I will call you as soon as I arrive in Beijing.
– “了” can also be used to talk about changes of state.
现在是12点，该睡觉了。(Xiànzài shì 12 diǎn, gāi shuìjiàole.) It is 12 o’clock now, it’s time to go to bed.
周末结束，明天要上班了。(Zhōumò jiéshù, míngtiān yào shàngbān le.) The weekend is over, and I have to go to work tomorrow.
– The particle “过” denotes that some action has done in the past. It is used to emphasize experience. Compare the following sentences:
他来过我们家。(Tā láiguò wǒmen jiā.)
He’s been to our house (in the past – he’s left now).
他来我们家了。(Tā lái wǒmen jiā le.)
He’s come to our house (and he’s still here – completed action 了).
You can use “过” and “了” in the same sentence. When this happens, you’re always dealing with a ‘change of state 了’, also known as ‘sentence 了’. ‘Change of state 了’ is like saying “it is now the case that”. Things have changed, or there is new information.
When this combines with “过”, you get something like “it is now the case that something has been done”. Sentences that combine “过” and “了” are also about specific objects, i.e. ones that the speaker and listener know about already.
你洗过澡了吗？(Nǐ xǐguò zǎole ma?) Have you had a shower?
你吃过药了吗？(Nǐ chīguò yàole ma?) Have you taken your medicine?