通过自动获取或人为地供给外源 DNA使受体细胞获得新的遗传表型，称为
A．转化
B．转导
C．转染
D．转座
E．接合
参考答案：A
The final exam _____ next Thursday. [ ]
A. will take place
B. take place
C. is taking place
D. takes place
Tina _____ have known the truth, or she would have told us.
A．mustn't
B．shouldn't
C．can't
D．needn't
