求翻译：星期天早上七点半在学校门口集合，骑自行车到动物园， 班级分为四组，第一，二组负责清理草坪上的垃圾帮工人清理垃圾袋和果壳，第三四组负责向游客宣传环保知识，第三组负责监督游客将垃圾带走，十二点在门口集合，各自回家吃饭是什么意思？

7:30 am Sunday collection at the school gate, ride a bike to the zoo, the class is divided into four groups, the first and second group is responsible for cleaning up the garbage on the lawn to help workers clean up garbage bags and shell, the third and fourth group is responsible for promotion to t

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Sunday morning seven and half in the school entrance set, ride the bicycle to arrive the zoo, the class and grade divides into four groups, first, two groups are responsible for trash helper person who cleans up in the lawn clean up the garbage bag and the husk, the 34th group is responsible to the

7:30 A.M. at the school gate on Sunday, riding a bicycle to the Zoo, the class is divided into four groups, the first, the second group is responsible for cleaning up garbage to help workers clean up the garbage bags on the lawn and the shell, and the 34th Group advises visitors to promote environme

Gather at the gate of school at half past seven on Sunday morning, get to the zoo by bike, the class is divided into four groups, first, two groups are responsible for clearing up the rubbish on the lawn to help workers to clear up disposal bag and shell, third four responsible for propagate environ