按照下面要求改写句子.例：The clipper ships were built in the nineteenth

按照下面要求改写句子.
例：The clipper ships were built in the nineteenth century.
They are nineteen century clipper ships.
1）The castle was built in the thirteenth century.
It was a thirteenth century castle.
2）The students are in their fourth year (at college)
They are the fourth years students.
They are the fourth-year students.