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问题 单项选择题

婴幼儿易患呼吸道感染的免疫因素是（）

A.呼吸道黏膜缺少分泌型IgA

B.呼吸道黏膜缺少分泌型IgM

C.呼吸道黏膜缺少IgD

D.呼吸道黏膜缺少巨噬细胞

E.呼吸道黏膜缺少补体

答案

参考答案：A

解析：婴幼儿体内的免疫球蛋白含量低，尤以分泌型IgA为低，且肺泡巨噬细胞功能不足，乳铁蛋白、溶菌酶、干扰素、补体等数量和活性不足，故易患呼吸道感染。

单项选择题

About a week ago, when I was playing basketball at our local park, I noticed a small group of boys picking on a smaller, skinnier boy. They were (21) him names and even pushed him to the ground and kicked dirt in his face. (22) I saw that, I walked over to the group.
I stepped (23) them and the smaller boy, and asked them politely what this boy had done worthy of (24) they were doing to him. One of the boys replied, "He’s weird. " At that, I asked one of the boys if he thought his friend was weird, and the (25) was "No." So, I asked another boy what the word "weird" (26) , and he said, "Different." That was my cue (暗示). I told them that everyone is (27) , and that they all looked just as different to the other boy as he did to them. They all stood (28) for a moment, and then the most amazing thing happened. One of the boys helped the small boy off the ground and then said sorry to him. He (29) to let him play with them.
I thanked the boy for being so (30) As I looked around, I realized that there were dozens of other people at the park (31) no one else had stopped to help this boy. I felt happy that the boy was p enough to stand up against his friends to (32) someone in need, but I felt sad that (33) else had even taken a second look.
I hope that my action helped them (34) that they could have made a difference with a little (35) , and maybe next time they will be the ones who choose to help.

Ⅱ. 完形填空

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通过下面短文，掌握其大意，然后再各题所给的四个选项(A、B、C和D)中选出一个最佳选项。

A．When

B．Before

C．If

D．Though
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填空题

孔与轴的配合有（）、（）和（）
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