All questions of adverbs (where, where, where, how many, why, why, how)
All other words connecting simple sentences as part of a compound sentence
(although, so far, if, if, because, because, so that.), And also (what, how, when).
The words “what, how, when” can be both subordinate unions and allied words.
Let us consider the cases when the named words are unions. In other cases, they are allied words.
How to determine the words “what, how, when” are allied words or unions?
1) “What” – is an alliance when it can be replaced by a colon. See the rule – when you put a colon
It seemed to me that a smile flashed across her lips (“what” can be replaced by a colon -> “what” is an alliance.)
2) “How” is an alliance when it can be replaced by another union. (as if, exactly, etc.)
Life changed its course, how the river changes the channel (“how” can be replaced by the word “as if” -> “how” is an alliance and is not a member of the proposal)
I’m just amazed at how much she loves you (“how” = “how much” – circumstance, can not be replaced by an alliance -> “how” is a union word)
3) “When” – is an alliance only in subordinate clause and condition (that is, from the main part we ask the question – “When?” Or “Under what condition?”)
The heart of soybeans aching when he saw these sunken cheeks. (You can ask the question “When?” -> the word “when” is an alliance)
Oh, the summer is red, I would have loved you, when it would not be dust and dust, but mosquitoes, and flies. (Condition -> “when” is a union)