要使'dog'变成复数，你加上复数词尾'-s'。

To make the plural of 'dog', you add the plural ___ending '-s'.

在英语中，词尾'-ed'常用于表示过去时。

In English, the ___ending '-ed' is often used for the past tense.

单词'children'有一个不规则复数词尾。

The word 'children' has an irregular plural ___ending.