Through can be used as a preposition or an adverb. When through is used as a preposition, it is followed by a noun. When it is used as an adverb, it is not followed by a noun.
Through means from end to end or side to side of.
- The River Thames goes through London.
- We drove through the desert.
Through can also be used to talk about entering at one side and coming out at the other.
- The road goes through the forest.
- The train went through the tunnel.
- She wouldn’t let me through.
To go through something is to examine it.
- We must go through the accounts. (= We must examine the accounts.)
Through can also be used to talk about time. It means from beginning to end of.
- He will not live through the night. (= He will die before morning.)
Through as an adverb
As an adverb through means from end to end, side to side or beginning to end.
- I have read the letter through twice and cannot understand it.
Through can mean ‘all the way’.
- Does this train go through to Bangkok? (= Does this train go all the way to Bangkok?)
- I was awake all through the night.
Through can also indicate the cause, etc.
- The accident happened through no fault of yours.