The use of "by far" is generally restricted to superlative forms.... You are by far the smartest around here..... correct
But with comparatives "by far" is awkward - You are far smarter than the others around here. .. correct

by far多用于最高级，而不是比较级。记住！

by far和far better

BCD 都是现在和过去比较，应该是现在和现在比较
E far better known 比by far better known 更符合使用习惯

D是一个倒装，应该是 Anton Chekhov is far better known for his plays than his short stories were（known for his plays）, 比较对象是AC和 short stories

by far到目前为止，语义冲突

mark:
D倒装又省略：were his short stories= AC is far better known for his plays than his short stories were (known for his plays)

far better known for A than for B.
A,B选项的by far是时间状语，代表了从过去到现在，和原句的语义在时间范畴上有冲突，故可直接排除。

2分03才做出来。原因在于没有第一时间找到split。大结构，转折是在by far ... but it was during 还是转折在作品上？这个可以迅速排除掉AB。再看CDE中小比较

A. The it was. . . that. . . construction introduces additional words that do not contribute to meaning. If by far is intended to modify is better known . . . it should be placed after known, or set off by commas, to prevent far from seeming to go with better. If by far is intended to modify better, this is incorrect usage.

老师， 有两点没明白：
1）it was during his lifetime that...这是强调？所以几个选项中其实后半句是没有错的？
2)D中，具有该关系的两者为Anton Chekhov和his short stories，这是真的不太明白。

问下，by far是不是一个使用完成式的 time indicator？

在C和E之间纠结了半天，还是错选C了

by far的意思是“到目前为止”。
it was 是什么呢？是强调吗？。。。

为什么我一门心思觉得非强调句不选……

看到一种解释：by far表示非常修饰形容词时，用于最高级的前面，或比较级的后面；
by far + 最高级
比较级 + by far

by far不是也可以表示“远、非常”的意思，通常与比较急和最高级连用吗？

A选项后半部分是否也有问题？即不能说Chekhov's stories made him popular（逻辑主语） was during his lifetime。