具有过敏毒素作用的补体的生物活性片段是()
A.C2a,C5a
B.C2a,C3b
C.C3a,C5a
D.C4b,C2a
E.C4a,C2a
参考答案:C
—Do you often go swimming _______ Sunday mornings?
—Yes. Why not _______ with me this Sunday? [ ]
A. on; go
B. in; to go
C. on; going
D. in going
转化催化剂短环和长环的堆比重不同,分别是1220Kg/m3和1210Kg/m3。