第2题: [单项选择]What is assumed in the article A. Parents can help youngsters find volunteer work. B. Most youngsters can find suitable paid summer jobs. C. City governments want teenagers to work for them in the summer. D. Some teenagers want a summer job. 参考答案:D
第35题: [单项选择]关于肺硅沉着症描述正确的是()。 A. 大于5μm的硅尘致病性最强 B. 硅酸导致巨噬细胞自溶 C. 硅结节内无免疫球蛋白 D. 纤维性结节是肺硅沉着症的早期病变 E. 胸膜常无病变 参考答案:B 答案解析:硅尘粒子越小致病性越强,较大的硅尘粒子多受阻于呼吸道防御的各个环节,一般小于5μm硅尘粒子方能吸入肺泡,被肺泡内巨噬细胞吞噬后,在二氧化硅的毒性作用下,巨噬细胞发生坏死和崩解。肺硅沉着症早期病变是细胞