Are there any ways to know whether Verbてくる is about time or space ?
My friend told me that
when the verb involves changing from a state to another state, ～てくる is usually about time,
when there's place available in the context, てくる is usually about space.
Are there any other ways to know?
I've never personally thought about it in terms of whether it's a change in time or space. I don't know that you need to specifically do that, since it behaves the same grammatically in either situation.
くる after a verb in TE-form simply shows that something will become an action or state, or an action or state will continue. There are times when it may become abstract in English, but it behaves the same in any Japanese sentence it is used.
頭が痛くなってきた。
My head has started hurting.
(My head came to a state of hurting, and is still in that state)
一人で子供を育ててきた。
I have raised my child on my own.
(I have been doing the action of raising my child up to this point)
台風が近づいてくる。
The typhoon will be getting close.
(The typhoon will get close, and continue to be close)
These all happen to deal with space or time, but more importantly modify the state of the verb they are attached to. So I think by simply looking at that verb, you should be able to see what it is that's changing.
I think you have to rely on the context. For example, consider
湿気が入ってくる
熱くなってくる
These could be both about space or time.
