题目

   My father became    91   （addict） to smoking cigarettes. As   92   result of smoking, he got lung cancer. And he was   93   danger of losing his life. His doctor didn’t allow him   94   (smoke) any more. My father had to take the doctor’s  95   (advise). As   96   as I know, smoking cigarettes has many other                                 dangers to humans. Every year, a lot of people die of the illnesses or they’re   97    (serious) injured in fires    __98    (cause) by smoking. And the number of pe当x=-2时，二次根式的值为（ ）A．1B．±1C．3D．±3