汗牛充栋的英文：
[Literal Meaning]
sweat/ox/fill/house
to have enough books to make the ox carrying them sweat or to fill a house to the rafters

[解释]
形容藏书非常多。

[Explanation]
an immense number of books

[例子]
他爸爸喜欢读书，家里有一万多本书，真是汗牛充栋了。

[Example]
His father enjoys reading and there are over 10,000 books in his apartment，which can fill the house to the rafters.

The crowning task would be to condense these voluminous still-accumulating materials
要完成任务，还得把汗牛充栋的，仍在不断增加的材料进行压缩。