What does write up mean?

[Tran]

English Language Tests, Intermediate level

ESL/EFL Test #200 "Phrasal Verbs (T to W)", question 10

Jim didn't have much time to ......... the contract.

(a) write about
(b) write over
(c) write up

English Language Tests, Intermediate level

ESL/EFL Test #200 "Phrasal Verbs (T to W)", answer 10

Jim didn't have much time to write up the contract.

Correct answer: (c) write up

Your answer was: incorrect
Jim didn't have much time to write about the contract.
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what does it mean write up in these sentence

[Mister Micawber]

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Write up = write.
.
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Native English teacher at Mister Micawber's