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

问题补充：

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

答案：

(答案→)A. came about

B. came back

C. came up

D. came along

解析：考查词组：A．came about发生B．came back回来C．came up想出D．came along一起来，how it came about that….?怎么会…?, 句意：我就是不能理解你怎么在这么短的时间完成这么多的工作。选A。