— How long have you been collecting shells?

— ______.

A．After I left school

B．Before I moved here

C．When I went to the beach

D．Since I was ten years old

标准电池的电动势随环境温度变化而造成的误差是（）。

A、系统误差

B、随机误差

C、疏忽误差

D、残余偏差