It is hard to forget.

这件事难以忘记。

youdao

When you see a logo, it is hard to forget that product or company.

当你见过一个标识，就很难忘记该种商品或其生产厂家。

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In 2001, I had eighteenth birthday, those beautiful blessing, my friend sincere eyes, sweetheart mild voice, everything lets my gratitude and it is hard to forget.

2001年我过了十八岁的生日，那些美妙的祝愿，伴侣朴拙的眼神，心上人平和的声响，一切都让我感恩而且难以遗忘。

youdao

Like many of U2's songs, it is an expressive love song with a melody that is hard to forget.

VOA: special.2009.04.10

No one should ever forget how hard it is to find success when life itself seems a joyless chore to be endured.

FORBES: Investing In Psychological Well-Being Pays Off With Income Gains

It is hard to beat Kenya for its unfettered access to wildlife, but visitors often forget that getting up close does not have to mean being confined in a vehicle.

BBC: Safari in Kenya without four wheels