当PEG浓度大于多少时，选择性沉淀循环免疫复合物特性消失()
A．1%
B．2%
C．3%
D．4%
E．5%
参考答案：E
---- Was it by cutting down staff _ _she saved the firm?
---- No, it was by improving work efficiency.
A．when
B．what
C．how
D．that
NULL指针分配的地址空间为( )。
A．16KB以下
B．4MB～2GB
C．2GB～3GB
D．3GB～4GB
