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【单选题】
抗体发挥负调节作用的主要机制是( )A.
形成抗原-抗体复合物,使抗原量下降
B.
形成免疫复合物后激活补体溶解免疫细胞
C.
与BCR竞争抗原或引起受体交联
D.
通过ADCC介导NK细胞杀伤免疫活性细胞
E.
IgM型抗体结合抗原,与B细胞表面CD32(FcγR II-B)结合,抑制B细胞活化
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【单选题】It's because he helped you ______ I'm ready to help him.
A.
why
B.
since
C.
so
D.
that
【单选题】听力原文：W: Are you being helped, sir? M: No, not yet. I'm trying to find a pair of shoes. You see, my feet are so big and it's difficult to get my size here. W: You've come to the right place, sir. Look,...
A.
A pair of trousers
B.
A pair of shoes
C.
A coat
D.
A dress
【单选题】Thank you for your help. If you___________us, I think we_________doing it now. [ ]
A.
hadn't helped; must have been busy
B.
didn't help; must have been busy
C.
hadn't helped; must be busy
D.
didn't help;must be busy
【多选题】管路中的压力损失将导致传动效率降低，油温升高，泄露增加，所以液压系统的管路应 ( )。
A.
缩短管路的长度。
B.
减少不必要的弯头
C.
限制流速
D.
减少不必要的管道截面突变
【简答题】Passing prehistoric-looking beaches and swamps on the way to the Haast Pass, we stopped off at Ship Creek and watched Hector dolphins (the world's smallest marine dolphin at 1 metre in length) surfing...
【单选题】It's ______ he helped you that I'm ready to help him.
A.
the reason
B.
for
C.
because
D.
since
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