It's too good to be true. It's too good to believe. 好的简直让人难以置信。too...to...
太好了，以至于不...
I don't believe what he said. 我不相信他说的。

Why don't you believe her?你为什么不相信她？
Don't expect me to believe you. 别指望我相信你。expect sb to do期望/指望某人做某事


A: Sorry, I didn't mean to be late. 抱歉，我不是故意迟到的。didn't mean to do...表示“不是故意做某事”
B: What's your excuse this time?你这次的借口是什么？
A: My mother is ill and I need to take care of her.我妈妈生病了，我需要照顾她。
B: Get out of it, you said it twice last week. 别瞎说了，你上周已经说过两次了。get out of it意为：“别瞎说了；别胡说了”，常用于口语表达中
A: Are you sure? I remember what I said last week was that my sister was sick. 你确定吗？我记得我上周说的是我妹妹生病了。
B: I don't think so, but it could be. 我可不这么认为，不过也有可能是这样。
A: You must believe me this time. My mother is really sick, she is in hospital now. The doctor said she has acute appendicitis. I just got out of the hospital and they said my mother needed an immediate operation.这次你一定要相信我。我妈妈是真的生病了，她现在在医院，医生说她得了急性阑尾炎，我也是刚从医院回来，他们说我妈妈需要立即动手术。
B: I don't buy your story. I've seen the message your mother sent me.我才不信呢，我已经看到你妈妈发给我的消息了。I don't buy your story意为：“我不相信你，我才不相信你说的鬼话”，还可以用：“I don't buy it”,it指代某人说过的话，这里的buy指的是“接受，相信”，俚语。
A: What? What did my mother send you?什么？我妈妈发给你什么了？
B: She said you stayed up late last night to do the homework, so you got up late this morning. Please be more punctual in the future. 她说你昨天晚上熬夜写作业，所以今天起来晚了。下次不要再迟到了。
A: I'm working on it. Trust me.  我正在努力呢，相信我。work on表示“从事于；致力于”
B: That depends on your performance. 那得看你表现。