题目

二次函数f(x)满足f(2+x)=f(2–x)，且f(a)f(0)<f(1)，则实数a的取值范围是______ 答案：                    The time he has devoted in the past 10 years________ the disabled is now considered________ of great value.A．to help；being B．to helping；to beC．to help；to be D．helping；being