adverb
1
BAD : It's time I gave you your photographs again.
GOOD : It's time I gave you your photographs back.
DUBIOUS : He'd like to have his bicycle again if you've finished with it.
GOOD : He'd like to have his bicycle back if you've finished with it.
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If you give something to the person who gave it to you, you give it back to them. When you mean 'to the person who had it before', 'to the place where something was before' etc, use back (NOT again ): 'He took the camera back to the shop and asked for his money back.' 'Shall I put these books back on the shelf?'
2
BAD : I'll phone you again in five minutes.
GOOD : I'll phone you back in five minutes.
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If you telephone someone after they have telephoned you, you call/ring/phone them back: 'Put down the receiver and I'll call you back.'
3
BAD : I would like to visit again some of these places.
GOOD : I would like to visit some of these places again.
BAD : I'll give you again my address.
GOOD : I'll give you my address again.
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Again (= a second time) usually comes after the object: 'It's wonderful to see you again.' 'Would you like to watch the film again?'
4
See REPEAT (↑ repeat )