问题
多项选择题
免疫防御功能包括（）
A.阻止病原微生物侵入机体
B.抑制病原微生物在体内繁殖、扩散
C.从体内清除病原微生物及其产物，保护机体生存的功能
D.清除体内变性、损伤及衰老的细胞
E.识别、杀伤与清除体内的突变细胞，防止肿瘤的发生
答案
参考答案：A, B, C
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免疫防御功能包括（）
A.阻止病原微生物侵入机体
B.抑制病原微生物在体内繁殖、扩散
C.从体内清除病原微生物及其产物，保护机体生存的功能
D.清除体内变性、损伤及衰老的细胞
E.识别、杀伤与清除体内的突变细胞，防止肿瘤的发生
参考答案：A, B, C
| 根据短文内容，用方框中所给词的适当形式填空。（其中有一词多余) | |
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| There are millions of stars in our sky. If you look 1________ the sky on a clear night, it is possible to see about 3000 stars. They 2_______ small, but they are really very big hot balls of burning gas. Some of them are huge, but others are much 3_______, like our planet Earth. The biggest stars are very bright, but they 4_______ live for a short time. Every day new stars 5______ born and old stars die．All the stars are very far away .The light 6_______ the nearest star takes more than four years to reach Earth.Hundreds of years ago, people 7________ stars, like the North star, to know which direction to travel in. Today you can still see that star. |