Ficoll密度梯度分层液主要用于分离外周血中的
A．粒细胞B．单个核细胞C．红细胞D．巨噬细胞E．血小板
参考答案：B
Which of the following statements is correct
A．The definition phase results in the Software Requirements Specificatio
B．Testing is optional in software life cycl
C．CASE tools can only aid in the design phase of a software life cycl
D．A change during a later phase does not require the documentation of all earlier phases to be update
n个顶点的强连通图的边数至少有
A．n-1
B．n(n-1)
C．n
D．n+l
