These culturally-transmitted systems must allpass through the filter of biology.
这些文化传播系统必定都受到生物因素的过滤。
2
The only rule for defining a filter is that it must let events of the desired kind pass and block all others.
定义筛选器的唯一规则在于，它必须允许所需类型的事件通过并阻止所有其他事件。
3
Again, I'll create a new filter type, pass in the regular expression closure named rfilter and execute some asserts to ensure that everything is peachy. All of this is shown in Listing 3.