— I saw Mr. Green at school this morning.
— No, it _____ him. He flew to Canada last week.
A：can be
B：must be
C：can't be
阅读下面这首宋词，完成小题。
鹧鸪天
【南宋】辛弃疾
欲上高楼去避愁，愁还随我上高楼。经行几处江山改，多少亲朋尽白头！
归休去，去归休，不成人总要封侯。浮云出处元无定，得似浮云也自由。
