（something/everything）___in your room is dirty!you must clean it!选哪个?我选的是something,但是书上的答案却是everything,

（something/everything）___in your room is dirty!you must clean it!选哪个?我选的是something,但是书上的答案却是everything,
（something/everything）___in your room is dirty!you must clean it!选哪个?
我选的是something,但是书上的答案却是everything,

（something/everything）___in your room is dirty!you must clean it!选哪个?我选的是something,但是书上的答案却是everything,
结合语境呗
你房间里的每样东西都很脏,所以选everything

everything 一切
something 一些

为了加强语气，意思是你房间里东西都这么脏还不清扫一下。