求翻译：由于一些学生在校园里乱扔垃圾，在墙上乱画，不注意校园的环境，使我们的环境有了很大的改变，现在很少有蝴蝶和鸟儿来唱歌，树木也少了一些，空气也没有以前新鲜是什么意思？

Because some students on campus littering, graffiti on the wall, pay attention to the campus environment in which our environment has changed dramatically, and now very few butterflies and birds to sing, the trees have a little something, no fresh air before

Due to some students on the campus, litter on the wall paintings and campus environment, lack of attention, so that our environment has changed considerably, it is now very rare butterflies and birds singing, the trees are also less, and the air is also no previous fresh

Because some students throw trash in the campus, doodles on the wall, does not pay attention to the campus the environment, enable our environment to have the very big change, now very little has the butterfly and the bird sings, the trees have also been short some, the air also did not have before

Due to some students at the campus litter, painted on the walls, no attention to campus environments so that our environment has been greatly changed, now little has butterflies and birds to sing, the trees is less and the air is no longer fresh

Because some students on campus littering, graffiti on the wall, pay attention to the campus environment in which our environment has changed dramatically, and now very few butterflies and birds to sing, the trees have a little something, no fresh air before