单项选择题
[听力原文] W: When will my watch be ready M: Well, it is 7:00 o’clock by my watch, and I’ll get it ready in a couple of hours.
A.At 9 A.M. B.At 9 P.M. C.At 2 A.M. D.At 12 P.M.
A.evolution B.distinction C.production D.depopulation
A.The four blood types are known as A, B, AB, and O. B.Blood type A contains red blood cells that have a substance A on their surface. C.Blood type B contains an antibody directed against substance A. D.Blood type AB contains antibody, but red cells in this type of blood neither contain both A and B substances.