我曾经再那个湖上面看到一条浮着的死鱼

我曾经再那个湖上面看到一条浮着的死鱼.
I have seen a dead fish floating on top of that lake.
或者
I once saw a dead fish floating on top of the waters on that lake.
或者
In that lake, I have seen a dead fish floating on top of the water.

我觉得第一个最好, 不过LZ看着选好了~~

i ever found a dead fish floating on that river.

I have to see that a floating above the lake of dead fish

我曾经再那个湖上面看到一条浮着的死鱼.
I have found a dead fish floating on that river.

I'd seen a dead fish floating on the lake.