toのつかない不定詞を原形不定詞と言う。

tbd

An infinitive without a 'to' attached is called a bare infinitive.

needless to sayは不定詞の慣用表現として紹介されることが多いです。

tbd

'Needless to say' is often used as an idiomatic expression in the infinitive.

不定詞の形容詞的用法には２種類あり、①限定用法、②叙述用法。②はもちろん主格補語です。

tbd

There are two ways of using the infinitive as an adjective, 1. attributive, 2. predicative. Naturally 2. is a subject complement.