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问题 问答题

内源性抗原提呈

答案

参考答案：

解析：是指内源性抗原被胞质溶胶中的蛋白酶体降解为小分子抗原肽后，与MHCⅠ类分子结合，形成抗原肽/MHC Ⅰ类分子复合物，供CD8+T淋巴细胞识别的过程。

选择题

下列关于力的理解中正确的是（　　）

A．物体静止一定是受到了静摩擦力的作用

B．甲用力把乙推倒，说明甲对乙的力大，而乙对甲的力小

C．当物体离开地面时不再受重力作用

D．力是矢量，不但有大小，还有方向
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单项选择题

Recently, I flew to Las Vegas to attend a meeting. As we were about to arrive, the pilot announced with apology that there would be a slight (16) before setting down. High desert winds had (17) the airport to close all but one runway. He said that we would be (18) the city for a few minutes waiting to (19) . We were also told to remain in our seats meanwhile with our seat belts fastened (20) there might be a few bumps(颠簸). Well, that few minutes turned into about four-five minutes, including a ride that would make a roller coaster(过山车) (21) by comparison. The movement was so fierce that several passengers felt (22) and had to use airsickness bags. As you might guess, that’ s not a good thing to have happen in a(n) (23) space because it only (24) to increase the discomfort of the situation.

About twenty minutes into the adventure, the entire airplane became very (25) There was now a sense of anxiety and fear that could be (26) noticed. Every passenger simply held on for dear life …except one. A (27) was having a good time！ With each bump of the (28) , he would let out a giggle (咯咯地笑)of delight. As I observed this, I (29) that he didn’t know he was supposed to be afraid and worried about his (30) . He neither thought about the past nor about the future. Those are what we gown--ups have learned from (31) . He was (32) the ride because he had not yet been taught to fear it. Having understood this, I took a deep breath and (33) back into my seat, pretending I was (34) on a roller coaster. I smiled for the rest of the flight. I even (35) to giggle once or twice, much to the chagrin(随恼) of the man sitting next to me holding the airsickness bag.

（33）（）

A．sat

B．lay

C．went

D．rode
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