Past tense For action verbs, from eating and - Cchatty

Past tense

For action verbs, from eating and sleeping to walking, running, or even studying: add le 了:

I went.
Wǒ qù le.
我去了。

I ate.
Wǒ chīfàn le.
我吃饭了。

I slept.
Wǒ shuìjiào le.
我睡觉了。

Non-action verbs (feelings) are no different from present tense; don’t add le 了. Non-action verbs of thought, feeling, and emotion, and verbs of knowing and informing include everything from “like” and “love” to “think,” “feel,” “understand,” “know,” “ask,” “tell,” etc.:

I liked him.
✔ CC: Wǒ xǐhuān tā.
我喜欢他。
✖ BC: Wǒ xǐhuān tā le.
我喜欢他了。
I came to like him.

Ten years ago I liked white clothing.
✔ CC: Wǒ shíniánqián xǐhuān báisède yīfu.
我十年前喜欢白色的衣服。
✖ BC: Wǒ shíniánqián xǐhuān le báisède yīfu.
我十年前喜欢了白色的衣服。

I loved her.
Wǒ ài tā.
我爱她。

I wanted to buy it.
Wǒ yào mǎi.
我要买。

Non-action verbs used to express asking or telling are exceptions to this rule IF they have a simple direct object:

I asked her something.
Wǒ wèn le tā yíjiàn shì.
我问了她一件事。

BUT:
Yesterday I asked her if she wanted to go shopping with me today.
Zuótiān wǒ wèn tā xiǎng bùxiǎng jīntiān hé wǒ yìqǐ qù mǎi dōngxi.
昨天我问她想不想今天和我一起去买东西。