公共标志用英语怎么说

"Public sign" 用英语可以说作 "public signage"。

来源："signage" 是 "sign" (标志) 的名词形式，"public" 是 "公共的" 的意思。

例句：

The public signage at the train station is clear and easy to read. (火车站的公共标志明确易读。)
The city is working on improving the public signage for its bike-sharing program. (这个城市正在努力改善公共自行车共享计划的标识。)
The public signage in the park is designed to help visitors navigate easily. (公园里的公共标志旨在帮助游客轻松导航。)