We must never be unworthy of our teachers' untiring and sincere teachings.

我们决不要辜负老师的谆谆教导。

His enthusiasm seems untiring.

他的热情似乎从不减退。

He is a man of untiring industry.

他是位孜孜不倦努力不懈的人。

Satisfaction of customers is just our untiring pursuit!

顾客的满意是我们不懈的追求！

Her untiring efforts finally gained the recognition of the world.

她的不懈努力终于得到了世人的认同。