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Phrasal verbs

Common combinations with back

Back forms several phrasal verbs. Back away, back out, back in, and back up are standard. Back by usually means support by someone.

Quick answer

How is back used with particles and prepositions?

Use back away for moving away cautiously, back out for withdrawing from an agreement, back in for reversing a vehicle, and back up for supporting or making a copy. Backed by means supported by someone or something.

The driver backed in carefully.
She backed out of the deal.
The claim was backed by strong evidence.

Choose the pattern by meaning

These forms are not interchangeable. Choose the construction by meaning, not by which preposition appears most often.

1
back away from + danger

Moving away carefully

Back away means move backwards to avoid something threatening.

The crowd backed away from the fire.
He backed away from the barking dog.
2
back out of + agreement

Withdrawing from a commitment

Back out of means decide not to do something previously agreed.

They backed out of the partnership.
She backed out of the interview.
3
back in + vehicle

Reversing into a space

Back in means move a vehicle backwards into an area.

He backed in without hitting the wall.
Please back in slowly.
4
back up + claim/file

Supporting or copying

Back up can mean support an idea or create a copy of data.

Can you back up your argument?
Always back up your files.
5
backed by + support

Showing support or evidence

Backed by describes support from people, money, or evidence.

The proposal was backed by investors.
Her report is backed by recent data.

See the difference in context

The same subject can take different constructions because each sentence answers a different question.

Construction
Example
Meaning
back away from
The animal backed away from the noise.
move backwards from something
back out of
He backed out of the contract.
withdraw from an agreement
back in
She backed in smoothly.
reverse a vehicle into a place
back up
Please back up your files.
support or make a copy
backed by
The campaign was backed by volunteers.
supported by someone or something

Common mistakes

Some combinations appear in real text but do not mean what learners often assume.

Missing of after back out

Back out normally takes of before the thing withdrawn from.

✕ She backed out the plan. ✓ She backed out of the plan.

Confusing back up and back in

Back up often means reverse generally or support; back in specifically means reverse into a place.

✓ He backed in to the garage.

Using back by as a movement phrase

Backed by usually means supported by, not moving backwards.

✓ The research is backed by evidence.

Quick practice

Choose the expression that matches the intended meaning.

1. They decided to back out ___ the project.
2. Please back ___ your documents before updating the system.
3. The policy was backed ___ medical experts.

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Frequently asked questions

What is the difference between back up and support?

Back up is more conversational and can also mean provide evidence or make a data copy.

Can back in be used without a vehicle?

Usually it refers to moving a vehicle backwards into a space.

Is back away always physical?

Mostly yes, though it can also describe avoiding a confrontation.

backfire on, in, as, at or with? backtrack on, to, in, after or by? "baffle by" or "baffle as"? "bake in" or "bake for"? balance by, in, on, with or between? ban from, in, for, by or on? "bang on" or "bang for"? "banish from" or "banish to"? baptize in, by, into, with or on? "bargain for" or "bargain with"? "bark at" or "bark in"? bathe in, by, on, with or for?

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