E-shopping when properly can save us a lot of time and energy.A. doneB. doingC. to doD.

问题补充：

E-shopping, when properly ,can save us a lot of time and energy.

A. done

B. doing

C. to do

D. is done

答案：

(答案→)A. done

B. doing

C. to do

D. is done

解析：考查非谓语动词。逻辑主语E-shopping与do之间的关系为被动关系，故用过去分词，相当于when it is done properly，选A。