问题
单项选择题
When an organism is completely encapsulated and preserved, it becomes a fossil, therefore turning into evidence of things that once lived.
A. thereby
B. as a result of
C. so
D. in the end
答案
参考答案：A
解析： therefore和thereby均为副词，表“因此”，但therefore后通常跟一个句子；而thereby后常接现在分词作状语。as a result of“由于”(as a result才表“因此”)，因此A为答案。