not only...but (also)...
连接两个并列的结构或句子。也就是说not only后面是什么结构，but also后面就是什么结构
She not only wrote the text but also selected the illustrations. (谓语动词）
她不仅写了正文部分，而且还挑选了插图。来源：《牛津词典》
She was not only intelligent but also very musical. 形容词表语
她不仅聪明，而且极具音乐天分。来源：《牛津词典》
Not only do you have to understand this, but you also have to capitalize on it. （句子）