YOU SAID:

I think I have just seen a frog

INTO JAPANESE

私はカエルを見ていると思う

BACK INTO ENGLISH

I think I am a frog.

INTO JAPANESE

私はカエルだと思います。

BACK INTO ENGLISH

I think that it is a frog.

INTO JAPANESE

私はそれがカエルだと思う。

BACK INTO ENGLISH

I think it is a frog.

INTO JAPANESE

私はそれがカエルだと思う。

BACK INTO ENGLISH

I think it is a frog.