第三句话不对,因为The school gave a medal to her for winning the writing competition这句修饰的是Tina,我觉得可以这么改：
Tina,who is given the school medal for winning the writing competition ,is a top student.
第三句话不对,因为The school gave a medal to her for winning the writing competition这句修饰的是Tina,我觉得可以这么改：
Tina,who is given the school medal for winning the writing competition ,is a top student.