重点讲解：
1. go overboard
做得过分（或过火）；
eg. Women sometimes damage their skin by going overboard with abrasive cleansers.
女性有时因过度使用磨砂膏而损伤了皮肤。
eg. He has a tendency to go overboard at their parties.
在他们的晚会上，他总是喜欢过分地表现自己。
2. fed up
厌倦的；厌烦的；腻味的；
eg. He had become fed up with city life.
他已经厌倦了城市生活。
eg. I'm just fed up and I don't know what to do.
我就是腻味了，不知道该怎么办。
3. back and forth
往返；
eg. He paced back and forth.
他来回踱步。
eg. Two boys were in the street, tossing a baseball back and forth.
两个男孩在街上来来回回地投接棒球。
4. tune out
走神；开小差；漠视；
eg. Whatever you're talking about, children rapidly tune out if you go beyond them.
不管你在说什么，如果孩子们听不懂，就会很快走神。
eg. Rose heard the familiar voice, but tuned out the words.
罗斯听到了熟悉的声音，但没注意听说的是什么。
