题目

阅读理解Since birth, I have worn atracheotomy tube (气切管) around my neck to help me breathe. When Iwas growing up, it was common for adults to tell me that I should wear colorfulscarves (围巾) so that other people wouldn't see it. Theywould say,You can't even tell it's there, as if my disability issomething to be ashamed of (羞耻). As a kid, I neverreally thought about my disability the way I do now. It was just how I lived mylife.Now I'm 26 years old, and I'mproud to call myself a disabled woman because I consider my disability to be apart of who I am. I travel around the world t数列{an}的前n项和为Sn=2n+c，其中c为常数，则该数列{an}为等比数列的充要条件是（ ）A．c=-1B．c=0C．c=1D．c=2