Which of the following pairs of molecules provides the most important second signal for B cell activation?
A. CD28 on T cells and B7 on B cells
B. CD28 on B cells and B7 on T cells
CD40 on B cells and CD40L on T cells
D. CD40 on T cells and CD40L on B cells
E. LFA-1 on B cells and ICAM-1 on T cells
查看答案
The membrane immunoglobulin expressed by mature B cells is
A. only mIgM
B. only mIgD
C. only mIgE
D. both mIgM and mIgD
E. both mIgE and mIgD
第一本海洋学综合教科书《The Oceans》的作者是（）。
A. 威廉·贝比
B. 威维尔·汤姆森
C. 莫里
D. 斯维尔德鲁普
马里亚纳海沟是已知的海洋最深处，深度超过11.3千米。
A. 对
B. 错
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