B The question of whether the rural migrant worker is better off materially than the urban working poor is irrelevant in assessing the problems that they face.
白勇语法里说介词+分词短语在句首必须判定逻辑主语,但在句尾就不用判断逻辑主语。这里我实在搞不懂因为前面它还说放句尾一定要看逻辑主语是主句主语还是被修饰动词的主语,这里又说不用看了,难道它意思是介词+分词放句尾要判断,如果是介词+分词短语就不用了,是这样吗?