题干
—_________?
—It's B.
A：Where's B
B：What's your name
C：What's this
答案(点此获取答案解析）
C
—_________?
—It's B.
A：Where's B
B：What's your name
C：What's this
、
为双曲线C：
的左、右焦点，点P在C上，∠
，则