题目

It surprised me—every time I saw Joe，he was smiling．It didn’t __41__ whether he had to stop at a stop light，or if he were the seventh person in __42__ at the bank，and the service stopped just before he got there．Joe __43_ smiled．It made me wonder why he seemed so _44__ every day． Having observed Joe with other people，I __45__ something else also．Joe asked people how they were doing，and really seemed to listen to their __46__．If someone were hurting，he had _47___ for him and kind words，and offered to __48__ in any way he could． It made me think．．设P（3，1）为二次函数f（x）=ax2-2ax+b（x≥1）的图象与其反函数f=f-1（x）的图象的一个交点，则（　　）A．a=12，b=52B．a=12，b=-52C．a=-12，b=52D．a=-12，b=-52