1. They work with an unbelievable speed.
    他们以令人难以置信的速度工作。

2. 公共查询·英语单词大全

2. It would be unbelievable that such an honest fellow should have betrayed his friends!
    这样一个老实人竟会出卖朋友，真难以置信！

3. There are many unbelievable aspects to this theory.
    这一理论有许多方面不可信。

1. 不可思议的；难以置信的；极好的；非常棒的
    If you say that something is unbelievable, you are emphasizing that it is very good, impressive, intense, or extreme.

    e.g. His guitar solos are just unbelievable...
           他的吉他独奏棒极了。
    e.g. The pressure they put us under was unbelievable...
           他们给我们施加的压力之大超乎想象。

2. 极其糟糕的；令人震惊的；令人无法相信的
    You can use unbelievable to emphasize that you think something is very bad or shocking.

    e.g. I find it unbelievable that people can accept this sort of behaviour...
           人们竟能接受这样的行为，我震惊不已。
    e.g. Yes, the music library burned, three or four double basses burned. It''s just unbelievable.
           是的，音乐图书馆被烧了，三四把低音提琴烧毁了。真是太不幸了。

3. 不可信的；不像真实的
    If an idea or statement is unbelievable, it seems so unlikely to be true that you cannot believe it.

    e.g. I still find this story both fascinating and unbelievable...
           我仍觉得这个故事既有趣又不太可信。
    e.g. I know it sounds unbelievable but I never wanted to cheat.
           我知道听上去难以置信，但我从不想撒谎。

1. beyond belief or understanding

    e.g. at incredible speed
           the book''s plot is simply incredible

    Synonym: incredible

2. having a probability too low to inspire belief

    Synonym: improbableunconvincingunlikely