Whenheknockedatthedoor,mymotherw

发布时间：2020-07-12 01:38:59

When he knocked at the door, my mother was busy ____ supper.












A.preparing for











B.in preparing










C.to prepare for










D.to prepare

网友回答

B解析“be busy (in)doing something” 忙于干谋士，要求接动词的-ing形式。准备的直接宾语是“supper”,故其前面不用介词for。
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