—What a hot summer night! The temperature may be above 40 degrees Centigrade again.

—Why not get ________　cold beer in the air-conditioned room, watching the second season of The Voice of China? That must be　________　great fun.

A．a; /

B．/; a

C．the; a

D．a; the

在同一条无差异曲线上有AB两点，它们所表示的效用：（）

A．相同

B．不同

C．条件不足，无法确定