I know that it was once in a blue moon that he would fail an important exam. So I don't think that he will turn grey because of this.

我知道他很少在重要的考试中失手，因此我不认为他会因此而愁白了头发。

youdao

She foretold that he would fail.

她预言他会失败。

youdao

She forecast that he would fail.

她预测他会失败。

youdao

"I knew of course that when examined again he would fail and be thrown out.

VOA: special.2009.01.03

I knew of course that when examined again he would fail and be thrown out.

VOA: special.2010.03.27

They were sure he would always fail.

VOA: special.2009.09.03

Mr Smith had been concerned he would fail his medical test because of his back injury, but said "everything's healed quite perfectly".

BBC: Man inspired by sister's rescue joins fire service

If he was in my class, he would fail the test.

WSJ: Deal May Ease Evaluation Plan

Judge Howard Riddle denied Assange's first request for bail at a hearing on December 7 on the grounds that there was a risk he would fail to surrender.

CNN: Sweden to appeal Assange bail decision Thursday