把3吨煤平均分成3堆,每堆煤重______吨,每堆煤是3吨煤的______.
把3吨煤平均分成3堆,每堆煤重3÷3=1吨,每堆煤是3吨煤的13.
故答案为:1,13.
As time went by, I eventually found Mary and I had ________.
A.in common a lot
B.a lot in common
C.in a lot common
D.a lot common in
在黏膜免疫防御中起主要作用的抗体是()。
A.IgG
B.SIgA
C.IgE
D.IgD
E.IgM