英语单项选择并求解释_the Department of Homeland Security identified more than 7000 sensitive dates spanning the next 20 years,it did manage to rule out several dates as future 9/11s.A since B because C though D when
问题描述：
英语单项选择并求解释
_the Department of Homeland Security identified more than 7000 sensitive dates spanning the next 20 years,it did manage to rule out several dates as future 9/11s.
A since B because C though D when
答
a，根据句子的意思来判断，后句did强调
答
选择B,从答案看,逗号前应该是一个从句,从内容上看,从句中描述的应该是原因,而主句表述结果,且由关键词“did”可以看出.排除CD.AB均是表示原因的从句的引导词,若为since引导的从句,则由主句时态可知identified前应该...