The twins have studied in this school B. Atwo years agoB．since two years ago C．for two ye

问题补充：

The twins have studied in this school B. A．two years agoB．since two years ago C．for two yeas agoD．since two years

答案：

解析：句意：这对双胞胎两年前就已经在这所学校里学习了。Since加时间点用于现在完成时时态的句子中；故选B。