Tim's mum is worried _____ her son's eyesight as he plays online games too much. [ ]

A. for

B. about

C. with

D. of

高速公路是具有6个或6个以上车道，并设有中间隔离带、全部立体交叉并具有完善的交通安全、服务等设施，专供汽车以不同速度行驶的专用公路。( )