with these students it's pronunciation that's the problem. 係字典見到呢個例子，呢個係咩句子結構？我唔明。the problem of these students is pronunciation 係咪一樣意思？

An Attempt to Answer only:-
"pronunciation" as the subject;
"problem" as the subject.
NB:-pronunciation is way in which English Language is spoken in Lessons in Pronunciation to study the pronunciation of English.It's the way in which a word is PRONOUNCED, which means your pronunciation is poor.