问求区分宾语从句，定从，主从。

这么说吧，根据从句在整个句子句子中所作的成分判断，作宾语即宾语从句；做定语即定语从句，删掉不影响句子主干信息；做主语即主语从句。当然，对应的先行词、关系代词有些区别。1.宾语从句：The teacher told us 【that nothing is difficult if you put your heart into it】。从句that nothing is difficult if you put your heart into it做动词tell的间接宾语。2.定语从句：He is the man 【whom/ that I saw yesterday】。从句whom/ that I saw yesterday做man的定语，表示他是“我昨天见到的”的那个男人。3.宾语从句+定语从句：he thinks that Lucy 【who is beautiful】 is ungly。从句that Lucy who is beautiful is ungly做think的宾语，其中还有一个从句who is beautiful做Lucy的定语，表示“漂亮的”Lucy。4.主语从句：【That she survived the accident】 is a miracle整个从句That she survived the accident做句子的主语，“他侥幸存活下来”是个奇迹。