OG 12th GMAT 句子分析 上题

题目

OG 12th GMAT 句子分析 上题
in 1995 Richard.Stallman,a well-know critic of the patent system,testified in Patent Office hearings that,to test the system,a colleague of his had manage to win a patent for one of Kirchoff's law,an observation about electic current first made in 1845 and now in virtually every textbook of elementary physics.
testified in Patent Office hearings that中 that是什么作用?hearing怎么理解?testify in .这个是主句吗?

答案

主句是Stallman testified that in Patent Office hearings
that是宾语指示testify的方法to test the system.
hearings是听证会