4. not only … but also 连接两个分句，并且 not only 位于句首时，第一个分句中的主语和谓语要部分倒装。例如：
Not only does the sun give us light, but also it gives us heat.
Not only did he speak English correctly, but he also speaks it fluently.
《新编英语语法》薄冰P633：Not only does he compose music, but he also play./ Not only does he have to type out the answer on a computer, but he also gets the computer to translate it into sounds.
《新编英语语法》章振邦1005：She was not only compelled to stay at home, but she was also forbidden to see her friends
英语语法大全上的例句是: Not only did they break into his office and steal his books, but they also tore up his manuscripts. 所以我个人认为在倒装的情况下,but also是可以被主语拆开的.
这里附上ring_cheng的观点:倒装时可以在短语中插入某类成分，如：not only did sb do sth, but sb also did sth (之所以前后都加入主语，不是为了连接主语，而是为了句子的对仗工整而补足主语，连接的其实是主语的两个不同的谓语动作。又因为not only在句首已经倒装过了，所以but also用正常语序即可。依然满足句子平衡的要求).如大全354中but also被主语+助动词拆开:
354.In 1978 a national study found that not only had many contractors licensed by a self-policing private guild failed to pass qualifying exams, they in addition falsified their references.
A. they in addition falsified their references
B. they had their references falsified in addition
C. but they had also falsified their references
D. they had also falsified their references(C)
E. but their references were falsified as well
