英语标志牌用英语怎么翻译?

sign

勿折花草：do not ruin trees and flowers.来宾登记: visitor registration.请勿践踏草坪: do not step into the lawn.请随手关门: please close the door behind you.勿乱扔废弃物: do not leave trashes.

The signs written in English 比如在报道一则新闻时：Why do the protesters in Iran have signs written in English? Is the public opinion of the American people that important or do they speak English in Iran now? http://www.reddit.com/r/politics/comments/8u4co/why_do_the_protesters_in_iran_have_signs_written/

1、 warning board Warning 报警，警告...warning board 标志牌，警告牌...Warning buzzer 蜂鸣器（倒车用）2. signboard Signal valve 信号阀...signboard 标志牌...signboard illumination 标志牌照明3. marking board 交通工程学 Traffic Engineering...标志牌 ?marking board...交通标志标线 traffic marking line4. denoter 标志牌：denoter