这句话的语法有无错?

He was not only very inquisitive, but also frequently offered intelligent opinions .
说明：
not only 和but also 连用 是“不仅。。而且。。”的意思；
主语在这个短语之前时（如该句），只用一个主语就行，本句中第二个he 可以省去。。

There is a minor grammatical error in it.

Try this:

Not only was he very inquisitive, but he frequently offered intelligent opinions as well.
or
Not only was he very inquisitive, but also he frequently offered intelligent opinions.
or
He was not only very inquisitive, but also frequently offered intelligent opinions.

不要As well 重复了得 not only…but（also)就已经是不仅……而且……