COMB in ADJ (与名词连用构成形容词)表示“无…的”，“不含…的” -free combines with nouns to form adjectives that indicate that something does not have the thing mentioned, or has only a little of it. For example, sugar-free drinks do not contain any sugar, and lead-free petrol is made using only a small amount of lead. (与名词连用构成形容词)表示“无…的”，“不含…的”