--How long did you spend s_____ this peoblem?---About half an hour.以s开头的单词 填什么?
问题描述：
--How long did you spend s_____ this peoblem?---About half an hour.以s开头的单词 填什么?
还有一道题China is f____ for the Great Wall.Would you like to go there with me.
答
solving
famous