重点讲解：
1. throw out 扔掉，丢掉(废弃物)；
In just one day, Americans throw out 136 million kilograms of packaging.
仅仅一天，美国人大约扔出一亿三千六百万公斤的成包垃圾i|x)lGM_@--!Rt=m;。
2. be supposed to do sth. (按计划或期望)应当，应该，须；
She was not supposed to go but she insisted on going.
不该她去，她偏要去]Tf1s^#CR7#r9YA)。
3. err on the side of 宁愿过于…；力求…；
They may be wise to err on the side of caution.
他们过于谨慎也许是明智的oN@EqptBjKwPR。
4. go by 遵循；遵照；
You can't go by what he says, he's very untrustworthy.
你不能根据他的话判断，他是很不可靠的na%kFqT4ZR.Y7。