英语翻译经市政府批准,全市鸣放防空警报,届时请全体市民保持正常的工作和生活秩序解决之后在补分!谢过大侠!

As approved by the municipal government,the air raid sirens will be ringing in the city.Please all the people(citizens) maintain normal order for work and life.
后面一句一般也可以翻成这样：
Please keep calm and maintain your behaviors as normal.
请勿惊慌,保持常态.