For example, as infants are able to balance sitting upright their hands are now free to handle objects, so 
(infants; are; able to balance sitting upright) (infants; to balance; sitting upright) (infants; sitting upright; ) (their hands; are so; T:now) (their hands; to handle; objects)
infants infants infants their hands their hands
are to balance sitting upright are so to handle
able to balance sitting upright
sitting upright
T:now
objects