世界上最大的平原位于_____ ，它位于_____。[ ]

A、亚马孙平原、南美洲

B、中央大平原、北美洲

C、东欧平原、欧洲

D、西西伯利亚平原、亚洲

Paying to see that movie seems foolish　　　you can see it on television for free.

A．before

B．though

C．when

D．once