题目内容：

2008was a great year,since when it_____great changes in China.
A .saw B .has seen C .has seen D.was seeing

优质解答

since过去某个时间点的句子,时态都是现在完成时.给你看几个例句吧：
The real estate market in Britain has been very hot since last year when the annual rate of increase in housing prices exceeded 10%.
英国房地产市场从去年以来一直十分活跃,去年全年房价涨幅超过10%.
Great progress has been made in medical work since liberation.
自解放以来,医药事业取得了巨大的进步.
Great progress has been made since the beginning of the pilot project and the implementation of the six key programs.
六大工程建设从试点和启动以来,取得重要进展.