Translation of "Undankbar" in English

Sie waren undankbar.

They were ungrateful.

Finde ich es unglaublich undankbar.

I find it incredibly ungrateful.

Er war seinem alten Lehrer gegenüber gänzlich undankbar.

He was far from thankful to his former teacher.

Nach allem, was wir getan hatten, war er immer noch undankbar.

After all we had done, he was still ungrateful.

Der Undank ist immer eine Art Schwäche. Ich habe nie gesehen, dass tüchtige Menschen undankbar gewesen wären.

Ungratefulness is always some kind of weakness. I have never seen diligent people who were ungrateful.