题目

第三部分 阅读理解 阅读下列短文，从每题所给的四个选项（A、B、C、D）中，选出最佳选项，并在答题卡上将该项涂黑。 We were driving in the right lane （车道）when, all of a sudden, a black car pulled out of a parking space right in front of us. My taxi driver stepped on his brakes, skidded（打滑）. And missed the black car’s back end by just inches! The driver of the black car. Who almost caused a major accident . turned his head angrily and started shouting bad words at us . My taxi driver just smiled and waved at the guy. I mean, my taxi 如果a是有理数，下列各式一定为正数的 [     ]A.          B.          C.           D.