第20题: [单项选择]What is the meaning of the underlined word "waterproof" in the third paragraph A. Covered with water. B. Full of water. C. Cleaned by water. D. Not allowing water to go through. 参考答案:D 答案解析:[解析] 判断题。根据常识,鸟的翅膀都是不透水的。构词法:proof与其他名词构成复合词表示“穿不透的”, “防…的”, “耐…的”。如: heatproof“耐热的”;rustproof“防锈的