"Japanese is not like Chinese!"
Translation:יפנית היא לא כמו סינית!
Sorry, made a mistake - I mean is it there because of the particular words that come after it, or some other reason? Because at other times, it's not necessary as an equivalent of the English 'is'. I wondered if the comparison used in the sentence (I'm referring to the use of כמו here) has something to do with it.
Well, if the subject is a proper noun (יַפָּנִית Japanese does not usually take a definite article), the copula is common, if an indefinite predicate (כְּמוֹ סִ֫ינִת) is heavier, i.e. in lenght or complexity, than the subject. But the negator לֹא can count as a sufficient link word in this case, so for this specific sentence it should be possible to leave the הִיא out.