<p>了 can also be a 尾語 (final particle) similar to 啊</p>
<p>When removing 了 from a sentence doesn't make the sentence invalid, that 了 is most likely not function as a 'complete marker' or 'change of state marker' but a final particle that serves to emphasize the sentence (also indicates the sentence has ended)</p>
<ul>
<li><p>Remove 了 from 先把借书证办了 and write 先把借书证办 would make the sentence invalid. The function of 了 here is to indicate the completion of the verb 办</p>
</li>
<li><p>Remove 了 from 我真想都买了 and write 我真想都买 would change the meaning of the sentence. The function of 了 here is to indicate the completion of the verb 买</p>
</li>
<li><p>Remove 了 from 当然是写作业了 and write 当然是写作业 doesn't change the meaning of the sentence, the function of 了 here is as a final particle (indicates the sentence has ended and put emphasis on the sentence, like an exclamation</p>
</li>
</ul>

CC BY-SA 4.0
2023-07-21T07:59:14.620Z
2023-07-21T07:59:14.620Z
Tang Ho
<p>The following are my opinions:</p>
<ol>
<li>When a sentence ends up in a verb, it requires an auxiliary word/particle to indicate the completion of the action is someone's interest -</li>
</ol>
<ul>
<li><p>先把借书证<strong>办了/好</strong>. - (It is in your interest), first to finish the application for a library card.</p>
</li>
<li><p>我真想都<strong>买了/掉</strong>. - (It is in my interest), I really want to sell all.</p>
</li>
</ul>
<p>Note that without the auxiliary word/particle 了/好/掉, the sentences are grammatically incorrect.</p>
<ol start="2">
<li>When the sentence ends up in a verb phrase (V + Noun), 了 is a modal particle for setting the tone, and it is optional:</li>
</ol>
<ul>
<li>当然是写作业<strong>了/啦/呀</strong>. = 当然是写作业.</li>
</ul>
<p>Note that while both mean the same, the former answer has a casual tone, and is less serious about the task (写作业) than the latter.</p>

CC BY-SA 4.0
2023-07-22T01:51:30.360Z
2023-07-22T01:51:30.360Z
r13
<p>Well, 了 can't be a “completion marker”, because nothing has been &quot;completed&quot;. You must go upstairs and do something.</p>
<p>Also, nothing has “changed”, because you have not yet gone upstairs, so 了 can't be a &quot;change of state marker“.</p>
<p>An intention has been stated, so look at 了 as emphasis.</p>
<p>You may replace 了 with 好， or with 好了。</p>

CC BY-SA 4.0
2023-07-21T08:12:08.153Z
2023-07-21T08:12:08.153Z
Pedroski
<p>As far as I know 了 has two main functions.
1st is the completion marker, and the 2nd one is change of state marker. Here are some examples in which I can't figure it out the function and necessity of 了.</p>
<ol>
<li>办公室在三楼，我们上楼去， 先把借书证办了。</li>
</ol>
<p>What's the difference between</p>
<p>先把借书证办了.</p>
<p>and</p>
<p>先把借书证办.</p>
<ol start="2">
<li><p>我真想都买了。</p>
</li>
<li><p>A: 你要做什么？
B: 当然是写作业了.</p>
</li>
</ol>

<grammar>
Function of 了 in 当然是写作业了
# Function of 了 in 当然是写作业了

(Asked by: username_0 on 2023-07-21)

As far as I know 了 has two main functions.
1st is the completion marker, and the 2nd one is change of state marker. Here are some examples in which I can't figure it out the function and necessity of 了.

1. 办公室在三楼，我们上楼去， 先把借书证办了。

What's the difference between

先把借书证办了.

and

先把借书证办.

2. 我真想都买了。
3. A: 你要做什么？
   B: 当然是写作业了.

**Tags:** grammar

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## 3 answers

### Answer by username_1 on 2023-07-21. Score: 2

了 can also be a 尾語 (final particle) similar to 啊

When removing 了 from a sentence doesn't make the sentence invalid, that 了 is most likely not function as a 'complete marker' or 'change of state marker' but a final particle that serves to emphasize the sentence (also indicates the sentence has ended)

* Remove 了 from 先把借书证办了 and write 先把借书证办 would make the sentence invalid. The function of 了 here is to indicate the completion of the verb 办
* Remove 了 from 我真想都买了 and write 我真想都买 would change the meaning of the sentence. The function of 了 here is to indicate the completion of the verb 买
* Remove 了 from 当然是写作业了 and write 当然是写作业 doesn't change the meaning of the sentence, the function of 了 here is as a final particle (indicates the sentence has ended and put emphasis on the sentence, like an exclamation


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### Answer by username_2 on 2023-07-22. Score: 2

The following are my opinions:

1. When a sentence ends up in a verb, it requires an auxiliary word/particle to indicate the completion of the action is someone's interest -

* 先把借书证**办了/好**. - (It is in your interest), first to finish the application for a library card.
* 我真想都**买了/掉**. - (It is in my interest), I really want to sell all.

Note that without the auxiliary word/particle 了/好/掉, the sentences are grammatically incorrect.

2. When the sentence ends up in a verb phrase (V + Noun), 了 is a modal particle for setting the tone, and it is optional:

* 当然是写作业**了/啦/呀**. = 当然是写作业.

Note that while both mean the same, the former answer has a casual tone, and is less serious about the task (写作业) than the latter.


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### Answer by username_3 on 2023-07-21. Score: 1

Well, 了 can't be a “completion marker”, because nothing has been "completed". You must go upstairs and do something.

Also, nothing has “changed”, because you have not yet gone upstairs, so 了 can't be a "change of state marker“.

An intention has been stated, so look at 了 as emphasis.

You may replace 了 with 好， or with 好了。


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