=Model.=—The teacher gave me a book, _and_ I read it.
_And_, a co-ordinating conjunction, connecting the two principal
clauses, _The teacher gave me a book_, and _I read it_.
=Model.=—The boy is strong _but_ lazy.
_But_, a co-ordinating conjunction, connecting the adjectives _strong_
and _lazy_.
=Model.=—His mother said _that_ he might go.
_That_, a subordinating conjunction, connecting the subordinate clause,
_he might go_, to the principal clause, _his mother said_.