—Who's singing in the park?
—It ________ be Ann. Ann is much taller.
A:must
B:can't
C:need
D:can
最早研制成功的汽车、飞机的动力机是( )
____ (This/What) is a ____(girl/boy).
What's ____(his/her) name?
____ (His/Her) name is Li Qiang.