Site maps rely on spiders coming to call on your site, but more aggressive methods can land your pages in the search index, too.
只有爬行器到了您的站点上，站点地图才会发挥作用，但是还有更加主动的使页面被编入索引的方法。
2
The maps show a widely recognized indicator known as the Palmer Drought Severity Index.
该地图展现了公认的指标—帕尔默干旱强度指数。
3
Fred Brooks: I collected maps as a kid. I had tried all kinds of ways to index my map collection, which got me interested in the notion of automatic data retrieval.