The better more natural way of writing that sentence would be "A Comparative Study of English and Chinese Body Language" because "body language" as in term in English from my understanding only appears in the singular form. There may be multiple styles of body language, but body language as a concept is a singular whole idea. I hope that helps! It is a bit abstract to understand why it's body language not languages--I'm sorry if it's confusing!

The sentence, "A Comparative Study of English and Chinese Body Language" is correct. The key word here is "and". In this sentence, it shows two different types (English AND Chinese) of the same subject, "Body Language". Therefore "Body Language" should be in the singular. Chelsea's response is therefore correct.

Well in this case you ll use the plural LANGUAGES cause you are tallking about two different body languages , the chinese and the english ,,, this makes it a PLURAL. If the sentence was "a comparative study of english ( or chinese ) body language... then you say LANGUAGE, it is one language --SINGULAR , it is just the same with other words in singular and plural forms ...more than one of a noun will be considered PLURAL and usually takes an (S) at the end of the word ,, this is the rule while some words have a different kind of plural for example : man becomes men in plural etc ....