原则：连接词和主句专一
2并列句
eg: Failing hips can be replaced ，clinical depression controlled，cataracts removed in a 30-minute surgical procedure.
3主从复合
（2）宾语从句
动词+连接词+句子 I have learned that love ,not time,heals all wounds.
动词+宾语+连接词+句子
介词+连接词+句子
动词+it形式宾语+宾语+连接词+句子 make it clear that+句子
(3)表语从句
系动词+连接词+句子 The reason for my return is that I left my keys behinds.
(4）定语从句
1修饰和限定名词
2连接两个具有共同名词的句子 I have five books of which the red is my favorite
3表示因果逻辑关系
识别：名词（句子）+连接词+句子