I thought I'd understood the differences until I actually had to use them more
often to express myself better. Since this is an old, recurring grammar topic,
I'll just lay out all possible forms I can think of below.

> 僕は--
>
> **勉強してる** :
>
> I am studying (as of now)
>
> **勉強していた** :
>
> I had been studying / had studied (until a certain point in time in the
> past)
>
> **勉強してくる** :
>
> I have studied / have been studying (until now, and will continue to do so
> until a certain point in the future)
>
> **勉強してきた** :
>
> I have studied / have been studying (until now)
>
> **勉強してきている** :
>
> I have been studying (until now, whether I will continue or not is not
> specified)
>
> **勉強してきていた** :
>
> I had been studying (until a certain point in time in the past)

**Problems:**

  1. If my understanding is correct, some of them seem to overlap.
  2. Do Japanese people nitpick about the different usages laid out above? (Regardless of how conscious this process is.)

どうぞよろしくお願いいたします。
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2018-09-21T09:21:04.167
61648
2018-09-21T13:40:06.033
27674
question
grammar て-form
How does ていた (from ている) compare to てくる and てきた？
You are right except 勉強してくる. It says nothing about the past or the present
time, but means "will study there and come back here" or "will have studied by
then".

As for the difference between 勉強してきた and …してきている, they describe the same
situation, however, the latter puts focus on the current state of the object
rather than the actions it has accumulated. So, for example, 殺してきた is likely
to continue to a story that tells how unforgibable the deed is, while 殺してきている
how dangerous the agent is.
CC BY-SA 4.0
2018-09-21T13:40:06.033
61649
2018-09-21T13:40:06.033
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61648
answer