经典用法couldn’t +动词+比较级（adj.or adv.）解析如下：
couldn’t +动词+比较级这个结构，表示最高级的含义，翻译时要灵活把握。
I couldn't agree more.我完全同意。
I couldn't feel happier.我感觉快乐极了。
The rest of the players are a great bunch of lads and I couldn't be happier.
剩下的选手是一帮很棒的小伙子，我太高兴了。
Quite honestly, I couldn't care less what they do.
说实在的，我才不在乎他们做什么。
Frankly, I couldn't care less what happens to him.
说实话，我才不管他出什么事呢。
I couldn’t have enjoyed myself more—it was a perfect day.
我开心极了，——这是完美的一天。（高考真题）
Are you satisfied with her answer?
Not at all . It couldn’t have been worse.
你满意她的答案吗？
一点都不满意。她的答案糟透了。（高考真题）
Have you heard of Wang Meng?
Yeah. She couldn’t have done better. She won China’s first gold medal at Turin.
你听说过王蒙吗？
是的。她做得再好不过了。她在都灵赢得了中国的第一枚金牌。
It couldn't be better.不能再好了/最好的。
I couldn't care less about gossip about celebrities.
我对明星八卦一点都不感兴趣。
could't agree less
完全不同意
couldn't be worse
再坏不过了，糟糕透顶
could't agree more
完全同意
couldn't be better
再好不过了，非常好
What did you think of the film last night?
It couldn’t be better.
“你认为昨晚的电影怎么样？”
“好极了。”
Personally, I couldn't have cared less whether the ice-cream came from Italy or England
就我来说，我根本不在乎冰淇淋是意大利产的，还是英国产的。
《柯林斯高阶英汉双解学习词典》
This was an extremely successful trip. It couldn't have been better.
这次旅行玩儿得真过瘾。
I really could not have wished for a better teacher
这个老师对我来说是再好不过的了。
《柯林斯高阶英汉双解学习词典》
The mood could not have been grimmer.
情绪低落到了极点。