后缀“-ness”添加到单词“sweet”的末尾形成了单词“sweetness”，将形容词变为名词。

The ___suffix "-ness" added to the end of the word "sweet" forms the word "sweetness," changing an adjective into a noun.

英语中一个常见的后缀是“-ly”，它通常将形容词变为副词。

A common ___suffix in English is "-ly," which often turns adjectives into adverbs.

你可以给动词添加后缀“-er”来表示执行该动作的人。

You can add the ___suffix "-er" to a verb to indicate someone who performs that action.