第4题: [单项选择]反应型阻燃剂多用于( )反应。 A. 生化 B. 物理 C. 化学 D. 缩聚 参考答案:D 答案解析:反应型阻燃剂作为一种反应单体参加反应,使聚合物本身含有阻燃成分。多用于缩聚反应,如聚氨酯、不饱和聚酯、环氧树脂、聚碳酸酯等。反应型阻燃剂具有赋予组成物或聚合物永久阻燃性的优点。
第15题: [单项选择]Questions 19 to 21 are based on the conversation you have just heard. A. Building relationship with outer space. B. Making profits. C. Creating a stepping-stone to scientific research. D. Fostering international scientific cooperation. 参考答案:D 答案解析:[听力原文] According to the man, what’s the benefit of constructing the international space station <