下列哪种物质是T细胞表面的协同信号分子受体()。
A.CD4分子
B.CD28分子
C.ICAM-1
D.CD40分子
E.CD8分子
参考答案:B
装有两只20英尺的集装箱车应判为()类车。
A.5
B.6
C.7
D.8
Only ____from university ____how difficult it was to make a good career.
A.when did I graduate; I realized
B.when did I graduate; did I realize
C.when I graduate; did I realize
D.when I graduated; did I realize