translation in language instruction sucks
thats just mho, in any case translation is not taking a sentence in replacing in it all the words with their target language equivalents, every sentence conveys or at least is supposed to convey an idea or create an impression or feeling in those who read/hear it, translation is trying to do the same in another language, convey the same idea or create the same impression or feeling, so whats the idea of your snetence? the idea is that there is a category of plains that have a special name coastal plains, and they lie on the continental border, plains that are not coastal plain dont lie on the continental border, so there are different forms your translated sentence can take, coastal plains are those that lie ont he continetnal border, plains that are called coastal lie on the continnetal border, think abt the idea or what your source sentence is meant to convey rather than abt how the words in it run together