Staring into his eyes, I could see a _______ look in his eyes.

A．puzzle

B．puzzling

C．puzzled

D．puzzley

流行性感冒病毒最容易发生变异的型别为（）

A.甲型流感病毒

B.乙型流感病毒

C.丙型流感病毒

D.乙型和丙型流感病毒

E.甲型和乙型流感病毒