阅读下面短文，根据以下要求：①括号内汉语提示；②该词首字母提示；③上下文语境提示，在每个空格内填入一个适当的英语单词，并将该词完整地写在右边相对应的横线上。所填单词要求意义准确，拼写正确。

Last week I went on an eco-travel with a travel agency.

All the way we enjoyed the beautiful scenery and f     air.

But a few of us picked flowers __________going sightseeing.

Some even tried to catch some birds. What was _________,

many tourists t              rubbish here and there.

I don’t think this is an eco-travel. A true eco-travel is a tour

that not only a        us to express our love for nature, but

needs our ______(责任)as well. As we enjoy the beauty of nature,

we should try our best to protect_____. And we should also try to

protect wildlife. A true eco-travel should be ___________ this:

take nothing away but your good ________(记忆); leave nothing

b        but all the green trees and the clean water.