1. 小心的;仔细的;谨慎的
    If you are careful, you give serious attention to what you are doing, in order to avoid harm, damage, or mistakes. If you are careful to do something, you make sure that you do it.

    e.g. Be very careful with this stuff, it can be dangerous if it isn't handled properly...
           这东西一定要小心,稍不注意的话就会有危险。
    e.g. Careful on those stairs!...
           走那几段楼梯要当心!

2. 仔细的;周密的
    Careful work, thought, or examination is thorough and shows a concern for details.

    e.g. He has decided to prosecute her after careful consideration of all the relevant facts...
           在认真考虑了所有相关事实后,他决定起诉她。
    e.g. What we now know about the disease was learned by careful study of diseased organs.
           我们目前对该疾病的认识是通过对病变器官的仔细研究得来的。

3. 当心的;小心的;慎重的
    If you tell someone to be careful about doing something, you think that what they intend to do is probably wrong, and that they should think seriously before they do it.

    e.g. I think you should be careful about talking of the rebels as heroes...
           我觉得你说话应该小心,不能把反叛分子当英雄。
    e.g. It is important, I think, for everyone to be careful about claiming victory.
           我想,每个人宣布胜利时都应该慎重。

4. 节约的;节省的
    If you are careful with something such as money or resources, you use or spend only what is necessary.

    e.g. You will have to make a special effort to train your child to be careful with her pocket-money...
           你得格外注意培养孩子的节俭意识，零花钱要省着花。
    e.g. It would force industries to be more careful with natural resources.
           这将迫使企业更加节约资源。

5. 越谨慎越好;再小心也不为过
    You can say 'You can't be too careful' as a way of advising someone to be careful, even when this seems unnecessary.

    e.g. You can't be too careful when a young child is near water.
           孩子在水边时,还是越小心越好。