Passenger leukocyte
参考答案：
过客白细胞，是指同种异型移植物中供者的APC和淋巴细胞，是参与同种异型排斥反应的重要APC。
电梯轿厢平层误差允许值为（）
A.5mm
B.10mm
C.15mm
D.20mm
If we forgave criminals, we might become a society of endless excuses _____ no one accepts responsibility for anything．
A．which
B．where
C．when
D．as
