Theythoughtaboutitforalongtime,butstillcouldnot

問題詳情：

They thought about it for a long time, but still could not ______ a solution.

 A. come  over                        B. come along with    

C. come  out                         D. come  up  with

【回答】

D

知識點：動詞

題型：選擇題