thank,感谢，-less,无，没有。

1. Soccer referees have a thankless task.

足球裁判的工作吃力不讨好。

2. Sometimes being a mother and a housewife felt like a thankless task .

做母亲和家庭主妇有时使人觉得好像是个受累不讨好的差使。

3. Nobody was keen to take on such a thankless task.

没有人愿意承担这种费力不讨好的任务.

4. It was a thankless job, so we choked him off before long.

那是一件吃力不讨好的事情, 所以我们很快就不让他做了.

5. Roosevelt was reluctant to undertake the thankless task.

罗斯福不大愿意承担这种徒劳无益的任务.