全球第一部药典是（）
A.《本草纲目》
B.《五十二病方》
C.《新修本草》
D.《神农本草经》
参考答案：C
I am tired. I ______ all day.
A．am working
B．have been working
C．worked
D．have been worked
Over the past decades,sea ice___________in the Arctic as a result of global warming. [ ]
A. had decreased
B. decreased
C. has been decreasing
D. is decreasing
