题目

A middle school teacher has been praised for going above and beyond （超出）the call of duty to help one of his students with her math homework while _____ social distancing guidelines.One day, 12-year-old Rylee Anderson had trouble figuring out how to ____ a math problem. ________her school being _______during the disease, her parents couldn't help her with the problem. After Rylee ____ her math teacher Waba for help, he replied with some ____ on how to work out the problem. However, he could tell that she was still __ at the homework. Since Waba was ____ that his student lived just down 若等差数列{an}的前5项和S5=25，且a2=3，则a7=（ ）A．12B．13C．14D．15