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?

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theyhavebeencollectingstampsfor10years在collectingstamps下画线了对画线部分进行提问()havethey()()for10years?theyhav

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?
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?

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?
What have they been doing for 10 years?