If I had only known then what I discovered long afterwards!

要是我当时就知道这个我很久以后才明白的道理就好了！

youdao

'If only I had known you then,' he said wistfully.

“要是我那时认识你就好了。”他向往地说道。

《牛津词典》

If only I had known a little bit more about accelerated and effective learning when I was still a student myself! That would have saved me a lot of frustration and, most of all, precious time.

如果在我还是学生时就多知道一点有关高效学习的知识，那将会使我减少很多挫折，最重要的是，节约很多宝贵的时间。

youdao

Good lord, if I had only known about your last segment about not enough male teachers, as volunteer art and music teacher myself and as a person who knows what it can be like picked on by female teachers in elementary school, a person with a rare autism.

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