② our classroom = ours
(our: 形容词性物主代词 classroom:名词 = ours: 名词性物主代词)
③ his cap = his
(his:形容词性物主代词 cap:名词 = his:名词性物主代词)
④ Those are her erasers.
(her erasers:形容词性物主代词 名词 = hers: 名词性物主代词)
Those are hers.
⑤ They are their pens.
(their pens: 形容词性物主代词 名词 = theirs:名词性物主代词 )
They are theirs.
