MAC
参考答案：
即膜攻击复合物，由补体系统的C5b～C9组成。该复合物牢固附着于靶细胞表面，最终造成细胞溶解死亡。
—Can you let me know _____ yesterday?
—Because the traffic was bad. [ ]
A. why did you come late
B. why you came late
C. why do you come late
D. why you come late
设Σ是椭球面：的外侧，，计算曲面积分
的外侧，
，计算曲面积分