I wonder what's the purpose of 了 in combination of "must, have to" verbs. Here are some examples:

  1. 我得把今天的练习做了。 I know without 了 it would mean "I must do today's exercises". But I don't know what changes does the particle 了 bring here? Is this 了1 or 了2?

  2. 我该回去了。 Without 了 it would mean "I must return". But I don't know how to translate this sentence with 了.

  3. 您不要出来了。 Without 了 it would mean "You shouldn't come out". What's the difference between the sentence above with "您不要出来".

  • 不要 = don't; 该 = should; 得 = have to; 了 can be a particle that indicates the verb is completed but it is a final particle in these sentences
    – Tang Ho
    Commented Apr 12, 2022 at 10:17

2 Answers 2


The word 了 usually doesn't change the meaning of the text.

1. The word 了 is often used after verbs and adjectives to mean that something has finished. 2. Also used at the end of a sentence or a stop which means that something will or has already changed


  1. (1) 我吃完饭了 —— I am done eating (吃 is a verb and it means something has finished)
  2. (1) 水位已经降了两米 —— The water level has been lowered by two meters (降 is a verb)
  3. (2) 春天要来了——Spring is coming (The season will change soon)
  4. (2) 天黑了——It's dark already (already changed)

When at the end of a sentence, 了 has two functions/meanings:

  1. to indicate a change of state - something has been completed. 長大了, 變老了, 水位降低了...

  2. to inform the beginning of an action.

  • 我得把今天的练习做了。(I must start to do today's homework)

  • 我该回去了。(I shall go home now)

  • 您不要出来了 = 您不要出来 (You do not need to come out), the former way is more polite. Also 您不出来 is often used too.

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