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：副词应用。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。