（ ）is known to the world, Mark Twain was a great American writer.
A、
As
B、
Once
C、
That
D、
It
【正确答案】：A
【题目解析】：
本题考查定语从句的连词。
as：正如；once：一旦......；that：那个；it：它。
句意：众所周知，马克吐温是一位伟大的美国作家。
所以本题选A。
（ ）is known to the world, Mark Twain was a great American writer.
（ ）is known to the world, Mark Twain was a great American writer.
As
Once
That
It
本题考查定语从句的连词。
as：正如；once：一旦......；that：那个；it：它。
句意：众所周知，马克吐温是一位伟大的美国作家。
所以本题选A。