thankless

形容词 thankless:

1. not feeling or showing gratitude- Shakespeare
   同义词：ungrateful, unthankful
2. not likely to be rewarded
   同义词：unappreciated, ungratifying

1. I did much for him but what I got was only his thankless complaints.
   我为他做了那么多，但得到的只是他不知感恩的抱怨。
2. She played a thankless role.
   她扮演了一个受累不讨好的角色。