for a fact

例句：

1. 1.I've been working on this project for a long time, and I have to admit that I'm not sure if it's really going to work out.For a fact, I think it might be a bit too ambitious.
   我在这个项目中工作了很长时间，我得承认，我不确定它是否真的能成功。确实，我认为它可能有些过于雄心勃勃。
2. 2. You know what?I've always thought that the sky is blue, but now I'm starting to wonder if it's just a fact. For a fact, there are actually many different shades of blue in the sky.
   你知道吗？我一直以为天空是蓝色的，但现在我开始怀疑这是不是真的。确实，实际上天空中有许多不同的蓝色调。
3. 3.The weather forecast says it will be sunny today, but for a fact, we're expecting some rain.
   天气预报说今天会晴天，但确实，我们预计会有雨。