Allowing our cities to be （） by cars has progressively affected children's independent mobility, for children have lost much of their freedom to explore their own neighborhood or city.

A．pervaded

B．diffused

C．dominated

D．intervened

肠道杆菌的O抗原存在于（）

A.鞭毛

B.荚膜

C.菌毛

D.脂多糖

E.芽胞