印刷术发明以前，类似托勒密所制的地图很少见，而且价格不菲，因为当时的地图必须以手工绘制。

Before the invention of printing, maps like Ptolemy's were rare and expensive because they had to be hand drawn.

youdao

作者认为格林当时关心利比里亚的奴役劳工状况，其在《没有地图的旅途》有一段秘密任务就是作为反奴隶制社会的耳目。

The author believes that Greene's concealed agenda in "Journey Without Maps" was to act as eyes and ears for the Anti-Slavery Society, concerned at that time about slave Labour conditions in Liberia.

youdao

随着研究结果在城市内的延伸，DARPA将有能力制出他们的虚拟地图。

And stretching those findings across the city will allow Darpa to build their virtual maps.

youdao