非限制性定语从句是对先行词作附加说明，即使去掉，句意仍完整。 限制性定语从句是主句先行词在意义上不可分开或漏缺的部分, 如去掉, 意义则缺失。如： He didn’t come on time，which made her angrier. He bought a book which was written by Chairman Mao.

2.省略不同