应该采取适当的措施限制外国旅游者的数量，努力保护当地环境和历史不受国际旅游业的不利影响。

  

An increasing number of experts believe that migrants will exert positive effects on

construction of city. However, this opinion is now being questioned by more and more city

residents, who complain that the migrants have brought many serious problems like crime and

prostitution.