（不急）i keep myself in good shape by running five miles a day.
问题描述：
（不急）i keep myself in good shape by running five miles a day.
i keep myself in good shape by running five miles a day.
起到什么作用?最好给几个例子.
答
by+动作ing是介宾结构做状语,这里by是指通过.方式的意思.比如,i go to school by bike,我骑车上学,即.通过骑车的方式.