求助一道SC题，感谢各位！

EricaKo

【OG18-P680-668题】

In a review of 2,000 studies of human behavior that date back to the 1940s, two Swiss psychologists, declaring that since most of the studies had failed to control for such variables as social class and family size, none could be taken seriously.

• A
  
  psychologists, declaring that since most of the studies had failed to control for such variables as social class and family size,
  
  
  
• B
  
  psychologists, declaring that most of the studies failed in not controlling for such variables like social class and family size, and
  
  
  
• C
  
  psychologists declared that since most of the studies, having failed to control for such variables as social class and family size,
  
  
  
• D
  
  psychologists declared that since most of the studies fail in controlling for such variables like social class and family size,
  
  
  
• E
  
  psychologists declared that since most of the studies had failed to control for variables such as social class and family size,
  
  
  

答案选E，不理解的是“none could be taken seriously.”是什么成分呢？这不是一个完整的句子吗？那就存在两个完整的句子还用逗号隔开？？如何理解呢。求教！

EricaKo

理解了，谢谢几位！

JIMmy97

declare that 后面是宾语从句的内容，即“since……, none could be taken seriously” 这是一个完整的句子。并不是什么插入语。

zhp_gmat

前半句（in a review....）是状语，不是个完整的句子，而none could be taken seriously是主句。比如
In 2017, I took my first GMAT exam.
in a review...的作用和in 2017是一样的。
A和B的declaring都修饰psychologists,所以主句没有谓语动词
C having failed修饰studies，所以相当于psychologists declared that the studies, none could... studies怎么了？没有谓语动词
D fail时态错，such like ungrammatical

请叫我小田

考插入语吧，修饰限定的应该是studies而不是psychologists，排除abc, such和like同时出现在d，排除