程度・範囲・強調N1
言わずもがな
needless to say... / not to mention... / better left unsaid
Structure
N + は言わずもがな、N + も
Explanation
① Aは言わずもがな、Bも means not to mention A, even B...; ② 言わずもがなのこと means something better left unsaid.
Examples
子どもは言わずもがな、大人までこの映画に夢中になった。
Needless to say, children—even adults—were captivated by this movie.
その件は言わずもがなのことだった。
That matter was better left unsaid.
Note
Sense ① is like はもちろん/はもとより; sense ② means something better left unsaid.