It is mandatory in morphological development: For example, apoptosis is what is happening to the cells comprising a tadpole's tail as it transforms into a frog.
(the cells; comprising; a tadpole's tail; T:as it transforms into a frog) (it; transforms; into a frog) (apoptosis; is; what is happening to the cells) Context(apoptosis is,List([59, 71))):(It; is; mandatory)
apoptosis is,List([59, 71))
the cells it apoptosis It
comprising transforms is is
a tadpole's tail T:as it transforms into a frog
into a frog
what is happening to the cells
mandatory