Online shopping when properly can save a lot of time money and energy.A. doneB. is d

问题补充：

Online shopping , when properly , can save a lot of time , money and energy.

A. done

B. is done

C. having done

D. doing

答案：

(答案→)A. done

B. is done

C. having done

D. doing

解析：考查状语从句的省略。此题when后面省略了it is,句意：网上购物当适当使用的话，会节省许多时间，金钱和精力。故选A。