detectiveyan

这个问题看了前人巨长的帖子好象还没有什么很DING的论。但是鉴于SC的至高无上原则“答案是比较出来的”所谓DING论也会有漏洞。谈谈自己的看法，TO HAVE DONE 一般强调表达时间上比谓语提前few people are known to recover from the disease after the appearance of the clinical symptoms本句的意思的是人们被知道康复是在康复发生之后，The Western world’s love affair with chocolate is well-documented: few people have been known to have tasted it for the first time without requesting more 主要表达的意思是一般事实所以不用TO HAVE DONE，可以根据时间指示词来看.