水的密度比油大，所以油会浮在水面上。

Water has higher ___density than oil, which is why oil floats on water.

这个城市的东部人口密度比西部高很多。

The ___densities of people in the eastern part of the city are much higher than in the west.

这份合同的条款密度太高，我需要律师帮忙解释。

The high ___densities of this contract's terms require a lawyer to explain them.