Question

5．自从我十五岁后，就习惯于帮着母亲做家务事．
Ihave been used to helping my mother do the housework since I was fifteen．

Answer 1

分析 have been used to helping my mother do．

解答 答案：have been used to helping my mother do．结合句意表示习惯于做某事用be used to doing sth，动作发生在过去并持续了一段时间，故用现在完成时have/has+过去分词，主语I，故have，be的过去分词been，帮助某人做某事help sb do sth，故答案是have been used to helping my mother do．

点评 used to do 过去常常做某事 
be used to doing 习惯于做某事 be used to do sth被用来做某事