Student or Learner
Is the following sentence right?
"Studies are one of his greatest Achille's hills"
That I'm not feeling well(According to the description given of the idiom)
There's nothing wrong with using phrasal verbs, though colloquial ones should be avoided where possible. It also depends on the subject; in technology phrasal verbs and nouns are often the correct terms, but in law, this is less likely to be the case.
I'm learning idioms through using english only.