若x+y=2a，x-y=2b则xy的值为[ ]

A.ab

B.a²+b²

C.a²-b²

D. (a²+b²)

Every athlete as well as some coaches who ____ to go to the Games ____ asked to be here before 7:30 am.

A．are; are

B．is; is

C．are; is

D．is; are