Because they do not show which elements of the sentence and sentence are related and grouped.
Explanation:
Structure of flat trees does not allow the visualization of elements of the sentence and sentence as grouped and related elements. This makes it seem that there is no sentence being analyzed, but a set of loose elements and without any kind of connection between them. For this reason, when using the tree structure, to make it less flat, intermediate nodes must be made throughout the structure.
of course they wouldn't understand if its not in their language. you would need to sign to them in their native language for them to understand. if included common gestures in ther languae mixed in with ASL it wouldnt make any sense to them.
