I don't agree. *比I can't agree.的语气还要强烈，给人一种直接反对的印象。
I know I'm correct. (我认为我是正确的。)
I don't agree. (我不这样认为。)
I don't agree with that.
I don't agree with you.
I agree. (同意。)
I can't agree. *“我不能同意你的意见”，比较礼貌的说法。
All politicians are liars. (所有的政治家都是骗子。)
I can't agree. (我不能同意。)
I can't agree with that.
I can't agree with you.
I doubt it.
Do you think it's true? (你觉得那是真的吗?)
I doubt it. (我怀疑。)
I don't think so.
It's not likely to happen. (才不会发生呢!)
We found out that he wasn't there. (我们发现他没有在那儿。)
That's not what you said.
You didn't say that.
I can't buy that! *buy除了“买”以外，还有“相信”、“承认”的意思。
I'm telling the truth. (我说的都是真的。)
I can't buy that! (我无法相信。)
That doesn't make sense. (那不合乎道理。)
That's ridiculous! (那太荒谬了。)
I refuse to believe that. (我不敢相信。)
Bad idea. *用于不同意对方的提议时。
Let's cheat. (我们糊弄一回吧。)
Bad idea. (馊主意。)
That's a bad idea.
That's not a good idea.
Not a good idea.