短语词组短语Begin seriously to do homework 着手认真做家庭作业begin to do sth 开始做某事;开始去做某事;起头做某事;开始做begin to do something 开始做某事begin to do sth purposefully 口〉全力以赴begin to do begin doing 开始做某事begin to do -began to do 开始做某事 返回 begin to do