not only but also用法有：若連接兩個成分作主語時，堅持就近原則，與靠近的主語保持壹致。not only放在句首，後面句子用倒裝結構等等。
not only but also意思是 ：不僅……而且……
1、若連接兩個成分作主語時，堅持就近原則，與靠近的主語保持壹致。如：
She likes not only apple but also orange. 她不但喜歡蘋果而且喜歡橘子。
Not only the students but also the teacher was invited.
不僅學生們被邀請，而且那位教師也被邀請了。
2、not only放在句首，後接句子時要用倒裝結構等等。
Not only are mothers not paid but also most of their boring or difficult work is unnoticed.
母親們不僅得不到報酬，而且所幹的乏味艱辛的活兒也很少被留意。