从动词/动名词的逻辑主语是否正确入手来筛选选项：
伴随状语的逻辑主语是主句主语，动词ing作介宾短语、定语、主语是动词的名词化，本身就是名词，没有逻辑主语
A，it should be soaked in liquid after being pounded，it being pounded，逻辑主语正确，但it指代错误
B，saffron threads should be soaked in liquid after pounding， after threads pound sth，逻辑主语错误

A、主要问题的wordy，但是单复数也是有问题的。
B、The principal error here is the misplaced modifier: 'to best extract their flavor' mistakenly refers to saffron threads, leading to the absurd conclusion that they are extracting their own flavor.
C、 The principal error here, though, is lack of parallelism: since the first half is 'soaking them in liquid', the second half should be 'pounding them with...'.我个人觉得being pounded暗含soaking them的人被pounded了，语意有问题
E、单复数的问题。

B: The principal error here is the misplaced modifier: 'to best extract their flavor' mistakenly refers to saffron threads, leading to the absurd conclusion that they are extracting their own flavor.

A，这里的it是应该指代threads，但是主谓不一致，同样可以排除E
B，pounding缺少逻辑主语
C，需要考虑soak 和 be pound的主语问题，但无论如何，主语应该保持一致，但是这很明显某个方法/人/others不可能既主动又被动，排除
D correct

状语，判断其发生动作的主语是否合逻辑

the best way ... is ... to verb.

B/D: To best extract their flavor作目的状语还是作主语，语意上，“最好的方式来获取st的风味是做……”比“做……，为了获得st的风味”更好。

C/D：C，soaking them是主动式，after being pounded是被动式，对比D的to soak them和after pounding them两个主动式，后者语意逻辑更优。

C，The best way is soaking them in liquid after being pounded, soaking作宾语，动词名词化，没有逻辑主语，随便谁soak the threads都可以，ok；after being pounded同样是动词的名词化，随便谁被pounded，错误，是threads被pounded
D， soak them after pounding them，二者都没有逻辑主语，随便谁soak them，随便谁pound them，ok
E，by soaking it in liquid after pounding it，随便谁soak them，随便谁pound them，ok，同样是it指代错误的问题

错选B，主语saffron threads to extract favor不通。
A E单复数，D比C前后更match

(B): to best extract的主语变成了saffron threads

B: The principal error here is the misplaced modifier: 'to best extract their flavor' mistakenly refers to saffron threads, leading to the absurd conclusion that they are extracting their own flavor.
C: You are right to be suspicious of the word 'being.' The principal error here, though, is lack of parallelism: since the first half is 'soaking them in liquid', the second half should be 'pounding them with...'.

pounded(碾碎） them with a mortar and pestle.

B的逻辑主语有误，mark一下。

if "after" is followed by a verb form, that verb form must be a gerund (-ING). hence "after pounding".
but "the best way ... is ..." must go with an infinitive (TO + verb), not a gerund. i.e., you must write "the best way is ... TO + verb".
it's unidiomatic to write "the best way is ... verbING".

B的话要是人就好了。。。

AB中，should 用法错误，且A中it 单数指代threads错，B中，to best extract作为opening modifier, 使得逻辑主语变为saffron threads, 有ST自己extract的意思，AB错；C being用法不当，且跟soaking them in 平行的话应该是 pounding them in;E中 it指代不当，同A;答案D

c和d选项解释下区别吧？我想着用being是表示客观事实吧？ 还有after后面的是不是用被动和主动都是可以的啊？