Where does this definition of be proficient in come from?
This entry for be proficient in is sourced from GetWord Corpus, one of the dictionaries and corpora merged into Lughet.
Is be proficient in a noun, verb, or something else?
In this entry, be proficient in is tagged as 2v..
What is Lughet?
Lughet is a free trilingual dictionary covering nearly five million entries across Uyghur, Chinese, and English, drawn from more than ten source dictionaries and corpora.