---Good to see you again. It’s almost three years we met last time.---Yes how time flies

问题补充：

---Good to see you again. It’s almost three years we met last time.

---Yes, how time flies.

A. until

B. before

C. while

D. since

答案：

A. until

B. before

C. while

(答案→)D. since

解析：It’s +一段时间+since +一般过去时，符合题意，故选D