not only...but also这个句型,放在句首也可以不倒装吗?

应该是课本上的错误,上课的时候你可以和老师讨论一下,一般来说不要太淤泥于语法,对于考试它占的分很小,对于运用语法的变化则更大.有时候英语里有些语法用的就是让你想不通,要真遇到了,记着可以这么用就行.
下面都是有关的信息,楼主要是感兴趣可以看看.
否定词开头作部分倒装
如 Not only…but also,Hardly/Scarcely…when,No sooner… than
Not only did he refuse the gift,he also severely criticized the sender.
Hardly had she gone out when a student came to visit her.
No sooner had she gone out than a student came to visit her.
典型例题
No sooner___ than it began to rain heavily.
A.the game began B.has the game begun
C.did the game begin D.had the game begun
答案D.以具有否定意义的副词放在句首时,一般采用倒装句(谓语前置).这类表示否定意义的词有never,seldom,scarcely,little,few,not,hardly,以及not only…but (also),no sooner…than,hardly… when scarcely… when 等等.
注意：只有当Not only… but also连接两个分句时,才在第一个分句用倒装结构.如果置于句首的Not only… but also仅连接两个并列词语,不可用倒装结构.
Not only you but also I am fond of music.