we have been classmates for three years she hasn’t left me much impression so I can’t r

问题补充：

we have been classmates for three years, she hasn’t left me much impression, so I can’t remember her after graduation.

A. Since

B. Although

C. Because

D. Unless

答案：

A. Since

(答案→)B. Although

C. Because

D. Unless

解析：句意：虽然我们同学三年，但是她没有给我留下深刻的印象，所以我毕业后不记得她了。四个选项的含义分别是：A. Since自从，因为，B. Although虽然，C. Because因为，D. Unless除非，因为我们是同学和我记不得她是转折关系，所以用although。所以选B。