China uses historical maps to claim about 90 percent of the sea.

中国使用历史地图声称拥有大约 90% 的海域。

After digging through historical maps and conducting field work, they found milldams were abundant throughout Pennsylvania.

在翻阅历史地图并进行实地考察后，他们发现宾夕法尼亚州到处都是水坝。