name the river whose mouth mountain is monbetsu and mouth place is monbetsu ?
SELECT DISTINCT var_uri where brack_open var_uri dbo_mouthMountain dbr_Monbetsu,_Hokkaidō sep_dot var_uri dbo_mouthPlace dbr_Monbetsu,_Hokkaidō sep_dot var_uri a dbo_River brack_close