YOU SAID:

This is a truly complicated sentence.

INTO JAPANESE

これは、本当に複雑な文です。

BACK INTO ENGLISH

This is a really complex sentences.

INTO JAPANESE

これは本当に複雑な文章であります。

BACK INTO ENGLISH

It is a complex sentence.

INTO JAPANESE

それは複雑な文です。

BACK INTO ENGLISH

It is a complex sentence.