He's got a dual personality - usually a quiet nice guy type, but when he flips, his character changes.

With all the kerfuffle since this morning I'd almost forgotten but we've still got the problem of the club members haven't we?

However, the preposition+relative pronoun (which) part becomes a relative adverb (where).

During his quiet youth his brain was slowly preparing itself to be the organ of those energies which he subsequently displayed.

Gulf nations are constantly menaced by war.

My father will retire at the age of sixty.

Carbon monoxide is a poisonous substance formed by the incomplete combustion of carbon compounds.

He divorced her after years of unhappiness.

She shouted for help, but no one came.

Did you possibly not notice until just now? Er, well ... it was just so beyond my imagination that ...