Some anthropologists believe that the genetic homogeneity evident in the world's people is the result of a "population bottleneck" -at some time in the past our ancestors suffered an event, greatly reducing their numbers and thus our genetic variation.
Some anthropologists believe that the genetic homogeneity evident in the world’s people is the result of a “population bottleneck”-at some time in the past our ancestors suffered an event, greatly reducing their numbers and thus our genetic variation.
A. at some time in the past our ancestors suffered an event, greatly reducing their numbersB.that at some time in the past our ancestors suffered an event that greatly reduced their numbers
C. that some time in the past our ancestors suffered an event so that their numbers were greatly reduced,
D. some time in the past our ancestors suffered an event from which their numbers were greatly reduced
E. some time in the past, that our ancestors suffered an event so as to reduce their numbers greatly,
有几个问题:1,破折号的用法,这里为什么一定要是人类学家believe that X-that Y中Y的内容,而不是对前面内容的解释说明?2,great reducing balabala为什么不能是our ancestors suffered an event的结果状语?comma,Ving不是既能表伴随状语又能表示结果状语吗?求大神指教!已晕。