问题补充:
The twins has studied in this school .
A. two years ago
B. since two years ago
C. for two yeas ago
D. since two years
答案:
A. two years ago
(答案→)B. since two years ago
C. for two yeas ago
D. since two years
解析:在表示时间时,ago前加一段时间,表示多久之前,用于一般过去时态。Since后接一个时间点,表示自……以来,用于完成时态。For后接一段时间,用于完成时态,和持续性动词搭配使用。句意:这对双胞胎自从两年前就在这所学校学习。结合语境可知选B。