I had to be really persistent and it was very hard work.

我必须非常坚持，这是非常艰难的工作。

youdao

If you want to succeed, you have to work hard and be persistent.

如果你想要成功，你必须努力工作，并持之以恒。

youdao

Selfless great simplicity, humility, her character, persistent, hard work, perseverance, indomitable spirit, she found two elements, polonium and radium, she won two Nobel prizes.

伟大无私的她、谦虚质朴的高尚品格，坚毅刻苦、锲而不舍的顽强精神，她发现了两种元素——钋和镭，她一生获得了两次诺贝尔奖。

youdao

The most important message, I guess I would tell you, though, is what I tell my daughters, which is that America remains a country where if you work hard and you don't give up and you are persistent, you can succeed.

WHITEHOUSE: The White House