混流泵由哪些主要部件组成？
参考答案：
泵体，泵盖，叶轮，泵轴，轴承盒，填料函
My grandfather is fon’d of talking about good old days, _____is often the case with old people.
A．when
B．as
C．that
D．what
选择素分子中与配体的结合部位是（）。
A.细胞浆区
B.C型凝集素结构域
C.补体调节蛋白区
D.表皮生长因子样功能区
E.多糖分子区
