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Phrasal verbs are usually two-word phrases consisting of verb+adverb or verb+preposition.
Like many other verbs, phrasal verbs often have more than one meaning.
Back up means reverse:
You'll have to back up your car so that I can get out.
Back up means support:
My wife backed me up over my decision to quit my job.
Can we switch the word order?
You'll have to back your car up so that I can get out.
My wife backed up me over my decision to quit my job.
Is there any hard and fast rule about the usage of phrasal verbs?