in this report there are still a lot of details___

to be cleared up
句子的意思是，报告中还有许多细节需要被清理
表示需要被清理，还没被清理，所以要用to

如果需要用being来表示正在被清理的话，整个句子需要这么写：
in this report there are still a lot of details that are being cleared up. that are需要被加进来，因为are必须在being前面，以表示它正在进行

to be cleared up

to do sth表将要

很详细的一楼