explain是动词。explaination才是它的名词，可做单数，也可做复数。
第三人称单数： explains现在分词： explaining过去式： explained过去分词： explained
相关介绍
This stage, the children's explaination to the world are attributed to the psychological causality.
这个阶段，儿童对世界的解释是归因于心理的因素。
For this reason, the journalist had an investigation yesterday, and found another different explaination given by the company.
记者昨天为此进行调查时，发现公司方面另有说法。
His book explains the theory for the lay public.
他的书为大众阐明了这个理论。
