在造型中，一般将物体在光的作用下所产生的明暗对比关系，称作（）关系。
A、明暗
B、黑白
C、透视
D、明亮
参考答案：A
My friend Li Xiao knows my hometown very well because he ______ there many times with me. [ ]
A. has been
B. has gone
C. had gone
D. went
对中性粒细胞有趋化作用的补体裂解产物是（）。
A、C1
B、C2a
C、C3b
D、C5a
E、C8
