反密码子是指[ ]

A．DNA上三个相邻的碱基对

B．mRNA上三个相邻的碱基

C．tRNA上的三个碱基RNA

D．rRNA上的三个碱基

—Don't you think it was strange that Fang Fang _______ going over a whole page in the last test on

history?

—Not at all. She is always absent-minded when doing things.[ ]

A. missed      

B. miss        

C. has missed  

D. had missed