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157. In the mod-1920s the Hawthorne Works of the Western Electric Company was the scene of an intensive series of experiments that would investigate changes in working conditions as to their effects on workers’ performance.
            

A.      that would investigate changes in working conditions as to their effects on workers’ performance
            

B.     investigating the effects that changes in working conditions would have one workers’ performance
                

C.      for investigating what the effects on workers’ performance are that changes in working conditions would cause
            

D.     that investigated changes in working conditions’ effects on workers’ performance
            

E.      to investigate what the effects changes in working conditions would have on workers’ performance
            

 A: their没有指代
                    

 A: their没有指代
            

B: correct

C: that没有指代
            

D: conditions’ effects 改变原意
            

E: changes in working conditions would have做定语修饰the effects，what the effects没有谓语

谢谢,但还是有个疑问:感觉was是不是构成了倒装，所以时态是一个过去完成时

正常语序主干为：the scene of an intensive series of experiments  was investigating 呢？