可以替代途径激活补体,并参与黏膜局部免疫的抗体是()
A.IgG
B.IgM
C.IgA
D.IgD
E.IgE
参考答案:C
Isn't it time you got down to ________ the papers?
A.mark
B.be marked
C.being marked
D.marking
球根植物一般用分球繁殖,这种繁殖方法和分吸芽、分根蘖等同为分生繁殖的方法。