これは大切な理論だ。
Sentence Analyzer
English Translation
This is an important theory.
Furigana
これは大切 な理論 だ。
Romanji
Kore wa taisetsuna riron da.
Words
此れ
(これ)
this (indicating an item near the speaker, the action of the speaker, or the current topic); this person (usu. indicating someone in one's in-group); now; here; I (me); certainly
は
(は)
topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis
大切
(たいせつ、たいせち)
important; necessary; indispensable; beloved; precious; dear; cherished; valuable; careful
理論
(りろん)
theory
だ
(だ)
be; is; indicates past or completed action; indicates light imperative