...but they also 是完全可以说的，它属于 not only…but also… 的一种变体。很不巧，在本人最近要出版的一个小册子里正好对这个问题有过探讨，引录于此，供参考！

1. but also 分开用

有时可将 but also 分开用，即将 but 视为普通的并列连词，用于连接两个句子，然后将 also 用于句中（用谓语动词用在一起）。如：

He’s not only very fast, but he’s also got marvellous technique. 他不仅很快，而且技术高超。

在较正式的文体中，有时还可将 but also 中的 also 置于句末。如：

You not only coin a neat phrase, but turn a girl’s head also. 你说的话说得很动听，让女孩子美得晕头转向。

有时，not only…but also 会出现在更复杂的句子中。如：

A knowledge of etymology and semantics will not only make the study of English more interesting, but will help you to understand what you read. It will also help you to remember new words. 词源学和语义学知识不仅使英语学习变得更有趣，而且有助于你理解所读的文章，甚至还能帮助你记忆生词。

2. not only 的变体

有时也可将 not only 改成 not just, not merely 等。如：

For a teacher to hit a child is not just morally wrong but also illegal. 对一个老师来说，打孩子不仅是不道德的，而且是违法的。

His experience spanned not merely politics, but also business and journalism. 他的经历不仅包括从过政，而且还经过商，从事过新闻工作。

3. but also 的变体

该结构在实际运用中有时也可说成 not only…but…too (as well)，即将其中的 also 改为 too 或 as well，但此时的 too 或 as well 通常应置于句末。如：

He not only washed the car, but polished it too (as well). 他不仅冲洗汽车，而且还擦拭了它。

Not only was Mr. Smith crazy, but Miss Mary was crazy, too. 不仅史密斯先生疯了，玛丽小姐也疯了。

这样用时，too 和 as well 前面的 but 有时也可以省略。如：

He not only heard it, he saw it, too. 他不仅听到了，也看到了。

Not only do the nurses want a pay increase, they want reduced hours as well. 护士们不仅要求增加工资，而且还要求减少工作时间。

4. 结构的缺省

(1) 缺省 also：not only…but also…的意思是“不但……而且……”，其中的 also 有时可以省略。如：

His name is known not only in Japan, but in China. 他不仅在日本出名，而且在中国也出名。

(2) 缺省 but：有时省略的不是 also，而是其前的连词 but，此时连两个句的标点通常是分号（因为分号相当于连词），但有时也有直接用逗号的。如：

Not only has she been late three times; she has also done no work. 她不仅仅迟到了3次；她还没干一点活。

He not only writes his own plays, he also acts in them. 他不仅是自编剧本，还饰演其中的角色。

注意，当该结构用于两个独立的句子时，but 必须省略。如：

He’s not only a good actor. He’s also a successful actor. 他不仅是个优秀的演员，而且也是一个成功的演员。

(3) 缺省 but also：与缺省连词 but 的情形相似，此时用于连接两个句子的标点通常是分号（因为分号相当于连词），但有时也有直接用逗号的。如：

Justice must not only be done; it must be seen to be done. 正义不但必须伸张，而且要让人看到正义得到了伸张。

These movies were not only making money; they were also perceived to be original. 这些电影不仅赚钱，而且被视为具有原创性。

He not only does Schwarzenegger and Groucho, he becomes them. 他不仅仅是扮演施瓦茨尼格尔和格劳乔，他已经变成他们。

The government not only has to do something, it must be seen to be doing something. 政府不仅必须采取措施，而且必须让人们知道它在采取措施。

有时句中的标点用的既不是分号，也不是逗号，而是破折号。如：

She not only entered the competition—she actually won it! 她不但参加了竞赛——而且居然获胜了!

(4) 缺省 not only

A reporter must first be a teacher but must also view his function as that of a diagnostician. 记者必须首先是教员，同时也必须把自己视为一个诊断师。

John was most famous for his poetry, but he was also a schoolteacher, a literary critic, and a musician. 汤姆最著名的是他的诗，但他同时也是教师、文学评论家和音乐家。