As many as 70% of the parents of deaf children never learn the language that will most likely be their child's primary form of communication.
(As many as 70% of the parents of deaf children; never learn; the language that will most likely be their child's primary form of communication) (the language; will most likely be; their child's primary form of communication)
As many as 70% of the parents of deaf children the language
never learn will most likely be
the language that will most likely be their child's primary form of communication
their child's primary form of communication