Our room is big,but theirs bigger than our.这里为什么用的是theirs不是t

Our room is big,but theirs bigger than our.这里为什么用的是theirs不是t our room is big,but theirs is bigger than ours.what"s on the Our room is twice bigger than theirs.改为Our room is _ _ _ _ _ Our house is thirty percent bigger than theirs in size. 改错；our new flat is certain bigger than theirs Our class room is( )theirs. Our classroom is ( ) ( )than theirs. Our meeting room is _______ theirs . Our classroom is __________larger than theirs. Our classroom is （ ）cleaner than theirs Our house is smaller than theirs. Our house is _________________ than theirs.