September 10th is _________ Day in China.
A：a teacher
B：Teachers’
C：Teacher
D：Teachers
根据句意及所给汉语提示，完成下列单词。
—Sorry. Mum. I won't do it next time.
（x2+y2）2﹣4（x2+y2）﹣5=0，则x2+y2的值为（ ）
