YOU SAID:

the tomatoes are not ripe and are sour

INTO JAPANESE

トマトは熟れていないので酸っぱい

BACK INTO ENGLISH

Tomatoes are sour because they are not ripe.

INTO JAPANESE

トマトは熟していないので酸っぱいです。

BACK INTO ENGLISH

Tomatoes are sour because they are not ripe.