题干
Brian told you that there wasn’t anyone in the room at that time, ___________?
A：was there
B：wasn’t there
C：didn’t he
D：did he
答案(点此获取答案解析）
C
A：was there
B：wasn’t there
C：didn’t he
D：did he
既是偶函数又是周期函数.若
，且当
时，
，则
的值为（. ）