1. 解释;说明
    If you give an explanation of something that has happened, you give people reasons for it, especially in an attempt to justify it.

    e.g. She told the court she would give a full explanation of the prosecution's decision on Monday...
           她告诉法庭她会在星期一对原告方的决定作出全面解释。
    e.g. There was a hint of schoolboy shyness in his explanation...
           他的解释中带有一丝学生的羞涩。

2. 理由；原因
    If you say there is an explanation for something, you mean that there is a reason for it.

    e.g. The deputy airport manager said there was no apparent explanation for the crash...
           机场副经理说那次飞机失事没有明显的原因。
    e.g. Digging further into the medical literature, I found out there was a scientific explanation for all this...
           进一步翻阅医学文献后我发现，这些都是有科学解释的。

3. 阐述;详细的说明
    If you give an explanation of something, you give details about it or describe it so that it can be understood.

explanation

    e.g. Haig was immediately impressed by Charteris's expertise and by his lucid explanation of the work.
           查特里斯的专业知识和他对作品浅显易懂的阐释立即给黑格留下了深刻印象。