问题补充:
The problem is hard but Tom hasa good idea to solve it.
A. caught up
B. came up with
C. caught up with
D. comn up wlth
答案:
A. caught up
B. came up with
C. caught up with
(答案→)D. comn up wlth
解析:句意:这个问题很难,但是汤姆已经想出了解决他的主意。Come up with提出,想出catch up with超过,赶上,结合语境可知用现在完成时have done , 故选D。