“有一件事情令我不开心的是我们有太多的作业”用英语怎么说?There is one thing makeing us unhappy that we have too much homework 这样说对吗？

正确，就是不太地道，另外是making不是makeing。
troubling us比making us unhappy更好点

One thing troubling me is that there are too much homework for us to do.
One thing troubling me is that we have too much homework to do .

making 是这样写而且如果要是making前面就应该加上逗号，而不加就应该是makes。这句话只有一个语法点的错误，其他的都应该是对的！

There is one thing which makes me unhappy is that we have too much homework to do.

把making改为makes就好；that前加is

One thing makes me unhappy is that we have too much homework

One thing that makes me unhappy is that we have too many jobs.

There is one thing makes us unhappy that we have too much homework

One thing that makes me bored is too much homework for us.
补充的说法是完全可以的。 只是把定语从句和先行词分开了。 完全可以的。