短文改错。

    It is five years now since I graduate from High School Attached to Harbin Normal University. Last Saturday,

the class that I was on held a get-together, which took us a long time prepare. It was indeed not easy to get in

the touch with everybody and set a well time for all of us. We all enjoyed this precious day greatly, remember

the time we spent together and the people they were familiar with. It was a pity which some of us were not

present as they had gone to abroad for further studies. Anyway, they called back or sent greeting card from

different places.

__________________________________________________________________________________________

药代动力学的几个重要参数表示符号

生物半衰期为( )。

A．K
B．Ka
C．F
D．V
E．t_1/2