_ in the 1900s most American towns and cities had a Main Street.A,As early as B,Early C,Early as D

题目

_ in the 1900s most American towns and cities had a Main Street.A,As early as B,Early C,Early as D
_ in the 1900s most American towns and cities had a Main Street.
A,As early as
B,Early
C,Early as
D,Earlier
请给出解释.

答案

B
as 后面不能跟in,所以AC不对,这个句子也没有比较所以d也不对