He made it in the end.but he didn't explain to us what great difficulty he had had _______ theproblem.A. working out B.to work out C.work out D worked out.答案是A,我选的是D,为什么,写出理由

来源：学生作业帮助网 编辑：作业帮 时间：2024/07/09 08:05:06
xݑJ0_ܩ0(i/| iM?ӻ*UcṁI畯`(^H8IrZ@<!nP!"۠%w}hDt, j7Xv,fAuj ~x@z[V2ԎMH -]J'oy~s&Yi6Z׬={aqTV uʱqY‘bh YC~׺q(<[u%-Bͺ3I_=D$0K,5-O^k9