Meaning of "bone up"

[Pupil]

Test No. incompl/advan-52 "Bones", question 6

We're expecting a visit from a French couple soon so I'll have to bone ......... on my French.

(a) in
(b) to
(c) with
(d) up

Test No. incompl/advan-52 "Bones", answer 6

We're expecting a visit from a French couple soon so I'll have to bone up on my French.

Correct answer: (d) up

Hello! Could you anyone tell me what does "bone up" mean?
Many thanks in advance
pupil
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[Torsten]

'to bone up on something' means 'to improve someting' so if you bone up your French you practise to get better.

TOEIC listening, photographs: In the Far East

[Pupil]

thank you, Torsten
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[Shzatf]

Alan, in your test you use the phrase bone up ON French .whereas in your reply to you say "so if you bone up your French you practise to get better." Here you did not use the word "ON your French " is it that both ' bone up your French and bone up "ON" your French are correct.Please do explain it to me . i'm confused. Thanks.

[Beeesneees]

Personally, I have only heard 'bone up on something'. Perhaps Torsten's reply was a typo.
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