I simply couldn’t understand how it ______ that you did so much work within such a short time．

1. A.
   came about
2. B.
   came back
3. C.
   came up
4. D.
   came along

I simply couldn’t understand how it _____ that you did so much work within such a short time．

I simply couldn’t understand how it _____ that you did so much work within such a short time．

A．came about        B．came back         C．came up          D．came along

I simply couldn’t understand how it _____that you did so much work within such a short time.

A. came back 　　B. came up 　　 C. came about 　 D. came along