91300
> 来週（明日）には忘れてる

Initially, this strikes me as odd, because I would expect 来週には忘れる. But it
seems to make sense: " _Come next week, (I) will have forgotten about it._ "
How would 忘れる work differently in such sentences? (random sentences extracted
from the web)

> 多分来週には忘れてるだろうな
>
> たぶん来週には忘れてるけど！
>
> どうせ明日には忘れてるだろうし友情的な意味で言っただけだろうな

Also, it seems to me は is indispensable here. Is that correct? Why?
CC BY-SA 4.0
2021-11-20T07:52:31.670
91279
2021-11-22T15:17:07.767
30454
question
grammar particle-は aspect
Why 忘れてる in「来週（明日）には忘れてる」?
て adds the perfect aspect, which is more natural as suggested by the English
version using perfect tense. 来週には忘れる is less natural, but not impossible.

Regarding は, you are right. This is because the sentence means 'by next week'.
来週忘れる would mean 'I will forget next week', which is unlikely (forgetting is
not a conscious action; as an side, 来週に does not fit in this case).

* * *

Cf. Suppose you have a task that takes another week. Then, （この仕事は）来週には終わる
sounds (to me) as natural as 来週には終わってる. Strictly speaking, the former suggests
that the task does not finish this week while the latter does not specify -
but I guess this is a technical differentiation and not that we really use
them differently.

If you talk about a TV series finishing next week, （このドラマは）来週終わる is more
natural than 来週には終わる mostly because the program is usually once a week.
CC BY-SA 4.0
2021-11-20T12:10:17.240
91280
2021-11-20T22:26:39.260
2021-11-20T22:26:39.260
45489
45489
91279
answer
I think the main difference lies in when the said action (instant-state-change
verb, 忘れる in your case) can happen. 来週には○○する implies something will happen
around or (shortly) before 来週 **but not now** , whereas 来週には○○している implies it
can happen **anywhere** between now and 来週.

[![図](https://i.stack.imgur.com/AFHUR.png)](https://i.stack.imgur.com/AFHUR.png)

In your situation, the difference between 来週には忘れる and 来週には忘れている is not very
important. But compare the following sentences:

  * 私は500年後には死ぬ。  
(The speaker is not an ordinary human because this sounds like he intends to
live at least for another 300-400 years. 私は500年後に死ぬ without は means he will
die strictly in 500 years, and you even need an ability to precisely predict
your future to say this.)

  * 私は500年後には死んでいる。  
(An ordinary human can safely say this. は is usually necessary, but it can be
omitted in a relative clause. 2年後に死んでいる人 and 2年後には死んでいる人 are interchangeable.)

  * 10年後には結婚したい。  
(He probably doesn't want to get married right now.)

  * 10年後には結婚していたい。  
(He may want to get married even now, and 10年後 is a worst scenario.)
CC BY-SA 4.0
2021-11-22T03:41:28.357
91300
2021-11-22T15:17:07.767
2021-11-22T15:17:07.767
5010
5010
91279
answer