第4题: [单项选择]下列哪项不属于慢性病的自然病程阶段( ) A. 危险因素出现 B. 致病因素出现 C. 体征出现 D. 合并症出现 参考答案:D 答案解析:[解析] 危险因素的作用过程分为六个阶段,也可以说是慢性病自然史:无危险阶段;出现危险因素;致病因素出现;症状出现(致病阶段);体征出现(发病阶段);劳动力丧失。
第27题: [单项选择]A. Some sea creatures developed vertebrae. B. The first giant squid was captured. C. Some sea creatures shed their shells. D. Sea life became more intelligent. 参考答案:C 答案解析:[听力原文] According to the woman, what happened 200 to 500 million years ago