要将“dog”变成复数，你添加复数词尾“-s”。

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

后缀“-ed”是过去式动词的常见词尾。

The suffix '-ed' is a common ___ending for past tense verbs.

单词“happiness”有词尾“-ness”，表示一种状态。

The word 'happiness' has the ___ending '-ness' which indicates a state.