题干
-----Do you know if the old man is still living?
----- I'm sorry. He _________. He ______ for two months.
A：died, has died
B：has died, has been dead
C：has been dead, died
D：has died, has dead
答案(点此获取答案解析）
B
的图像关于直线
对称，它的周期是
，则（ ）