The mountain village is my hometown.   I spent   _____   merry night there when I was young.

A．a great many

B．plenty of

C．many a

D．a great deal

克雷伯菌属细菌的分群和分型主要依据是（）

A.H抗原和K抗原

B.K抗原和O抗原

C.O抗原和H抗原

D.B抗原和K抗原

E.Vi抗原和O抗原