问题描述：
they have been collecting stamps for 10 years
在 collecting stamps下画线了 对画线部分进行提问
( ) have they ( )( )for 10 years?
在 collecting stamps下画线了 对画线部分进行提问
( ) have they ( )( )for 10 years?
问题解答：
我来补答展开全文阅读