lest

1. CONJ If you do something lest something unpleasant should happen, you do it to try to prevent the unpleasant thing from happening. 以防[正式]

I was afraid to open the door lest he should follow me. 我儅時害怕打開那個門惟恐他跟蹤我。

And, lest we forget, Einstein wrote his most influential papers while working as a clerk. 而且，爲了不使我們忘記，愛因斯坦在做小職員的時候寫了他最有影響的論文。