如果要给病人输大量的血，输血的原则是 [ ]
A．输入0型血
B．输入A型或B型
C．输入AB型血
D．输入同型血
答案：D
Had it been possible I would have gone to the movies, but I ________________ busy.
A．had been
B．am
C．was
D．would be
SQL语句中的DROP关键词的功能是( )。
A．创建表 B．在表中增加新字段C．从数据库中删除表 D．删除表中记录
