31. It’s not easy for experts to ______
题型:选择题
问题:
31. It’s not easy for experts to ______ H1N1 flu in humans from regular human seasonal influenza.
A.distinguish
B.separate
C.define
D.recognize
31. It’s not easy for experts to ______ H1N1 flu in humans from regular human seasonal influenza.
A.distinguish
B.separate
C.define
D.recognize