the words意即某人說(shuō)的話.如Please tell me in your own words.
這里,words是復(fù)數(shù)形式,所以其謂語(yǔ)或系詞須用復(fù)數(shù).
they use：這里是一個(gè)定語(yǔ)從句,用來(lái)修飾the words.
謂語(yǔ)的單復(fù)數(shù)形式與賓語(yǔ)無(wú)關(guān),而只跟主語(yǔ)相關(guān).如：
You are a boy.
所以,本句為：
the words they use are called a language.