There’s also a region of low-density that could be a section of the hominid’s brain.
还有些低密度区域，很可能是原始人的大脑。
2
This section of the course develops the mathematical concepts used in statistics. Three ideas are essential: Random Variable, Density Functions, and Expectations.
此部分课程扩展了统计学中的基本数学概念。三个基本想法如下：随机变数，密度函数与期望。
3
It is made clear in the third section that the density distributions of visible matter and invisible matter are quite different from each other.