explanation 
英 [ˌɛkspləˈneɪʃən]  美 [ˌɛkspləˈneɪʃən] 
n. 说明，解释；辩解

例句：
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。

There was a hint of schoolboy shyness in his explanation. 

他的解释中带有一丝学生的羞涩。

It's my ulcer,' he added by way of explanation. 

“那是因为我得了溃疡。”他补充解释说。

It's the only explanation I can think of. 

这是我能想到的解释。

There was no reasonable explanation for her decision. 

没办法合理解释她的决定。

There must be some explanation for this. 

这事一定是有原因的。