The Chinese grammar particle 了 (le) has several different uses. Below, we will discuss how to use 了 to indicate a change, how to use 了 to show a completed action, and a fixed 了 structure to express a feeling of excess/extremes. These 了 structures are typically found in HSK 1.
The grammar particle 了 appears at the end of a sentence to emphasize a change in state or situation. Here are some examples of “change 了” grammar:
Nǐ nǚ'ér jǐ suìle?
How old is your daughter?
In this question, the particle 了 emphasizes a change in the daughter’s age. Children are always growing, so their age does not remain the same. The daughter has aged since you last asked her age.
What time is it?
As with the above example, 了 here emphasizes a change in time. Time is constantly changing, so 了 here emphasizes the time change. The time has changed since you last looked at the clock.
It is raining.
Finally, here 了 indicates a change in the weather. For example, it was not raining earlier, but is raining now (meaning it has started to rain since you last checked).
The grammar particle 了 is used at the end* of a sentence to indicate that the verb (or action word) of the sentence is complete. Here are some examples of “completion 了” grammar:
Wǒ hē kāfēile.
I drank coffee.
In this sentence, 了 indicates that the verb 喝 (to drink) is finished. You drank the coffee in the past and are no longer drinking coffee now.
Wǒ mǎi píngguǒle.
I bought apples.
Like the above example, 了 shows that the verb 买 (to buy) is complete. You bought the apples in the past; the action of buying them is done.
*When including an amount or quantity in the sentence, 了 changes its position, moving to immediately after the verb. For example:
Wǒ hēle yībēi kāfēi.
I drank one cup of coffee.
Adding the amount of “one cup” to the sentence causes the particle 了 to move to right after the verb 喝.
Wǒ mǎile bù shǎo de píngguǒ.
I bought quite a few apples.
Like above, adding the quantifier “quite a few” causes 了 to move to right after the verb 买.
This use of 了is a fixed structure, meaning it will never change. This 了 structure is used to express a degree or excess or extremity. You can use both positive and negative adjective in this structure. For example:
Tài piàoliang le!
Tài rè le!
It’s so hot!