In the hopes that someone could answer my question, I posted it to an online forum. In the hopes that they wouldn't be seen, the group snuck out of the schools back fire escape. I bought a size smaller, in the hopes that it would fit after my diet.

People have provided some good examples. As you may have noticed, in the HOPE (singular) is more common, more possibly more correct.

Hi 👋我想提高我的汉语水平，我叫阿尔特姆，我发现了您是中国人，您可以不可以帮助我？

I study for my exam in the hope (singular) that I will pass. He was well-behaved in the hope that he will be released from detention early. I hope this helps!

Thank the teachers for their answers.