417. Proper measures must be taken to limit the number of foreign tourists and great efforts should be made to protect local environment and history from the harmful effects of international tourism.
应该采取适当的措施限制外国旅游者的数量，努力保护当地的环境和历史不受外国游客的负面影响。

六级词汇讲解:
本句是被动语态使用的典型范例，两个并列句由and连接，不仅避免了人称做主语，还保持了句子前后的一致性。take measures to do sth.意为“采取措施做某事”；make efforts to do sth.意为“努力做某事”；protect sth. from sth.意思是“保护某事物不受另一事物的影响”。

句型拓展:
The property taxes on the residents in the community will be raised.
社区居民的房产税将会提高。
Initially, housing and farmland were created and established, and industry eventually followed.
一开始，人们修建房屋，开垦农田，后来又发展工业。
Parents should be encouraged to send their children to nursery schools, which will bring about profound impacts on children and families, and even the society as a whole.
应该鼓励父母将他们的孩子送到幼儿园，这对孩子、家庭，甚至整个社会都将产生深远的影响。