你试着把主句和先行词去掉,看从句完不完整.你去试下.
Is this the factory which ／that makes TV sets去掉主句和先行词后:makes TV sets 完整的应该是the factory makes TV sets
再如:I like the place where the people are friendly.去掉主句和先行词后the people are friendly 所以先行词是地点状语
He is the man who ／whom ／that I think to be worthy of our praise．去掉主句和先行词后I think to be worthy of our praise应该是:I think the man to be worthy of our praise