1
sb reddens
不及物用法，常指人因情绪而脸红。
Her cheeks reddened when she saw him.
她看到他时脸颊变红了。
变红；脸红
reddens — third person singular of redden
先理解核心含义，再看它在真实句子里的用法。
变红；脸红
to become red or redder
Her cheeks reddened when she saw him.
她看到他时脸颊变红了。
变红或更红。
To become red or redder.
使变红或更红。
To make red or redder.
redden
Base
原形
reddens
3rd person
第三人称单数
reddening
-ing
现在分词
reddened
Past
过去式
reddened
Past participle
过去分词
The sky reddens at sunset.
天空在日落时变红。
She reddened when the teacher praised her in front of the whole class.
老师在全班面前表扬她时，她脸红了。
The autumn leaves redden as the weather turns colder.
天气转冷时，秋天的树叶变红了。
The sunset reddened the entire sky.
夕阳把整片天空染红了。
不及物用法，常指人因情绪而脸红。
Her cheeks reddened when she saw him.
她看到他时脸颊变红了。
及物用法，表示使某物变红。
The cold wind reddened his nose.
冷风把他的鼻子吹红了。
与with连用，说明脸红的原因，如羞愧、愤怒等。
He reddened with anger.
他气得脸红了。
Not this
I reddened my face when I saw her.
Use this
My face reddened when I saw her.
redden 作不及物动词表示“变红”，用于主语直接变红；作及物动词时表示“使某物变红”，但“使脸变红”不自然。汉语常直接说“脸红”，英语应用不及物结构。
Not this
He redded the cloth with dye.
Use this
He reddened the cloth with dye.
redden 的过去式和过去分词是 reddened，不是 redded。学习者常误按规则动词形式变化，但 redden 是规则动词，直接加 -ed。
Focus on the distinctions below. Other candidates are kept compact until a reliable usage note is available.
脸变红
His face reddened with embarrassment.
他尴尬得脸红了。
容易脸红
She reddens easily when she is nervous.
她一紧张就脸红。
天空变红
The sky reddened as dawn approached.
黎明临近时，天空变红了。
树叶变红
The leaves begin to redden in October.
十月份树叶开始变红。
染红天空
The fire reddened the night sky.
大火映红了夜空。
Use reddens naturally, then get feedback on meaning, tone, grammar, and phrasing.
Revisit a common error or keep this word in your review list.
redden中有两个连续的d，像害羞时两颊红晕，记住：变红。
语域：formal 常见场景：文学作品或书面叙述、描写脸色因尴尬、激动而变红、描写自然景物颜色变红 redden 多用于书面或较正式的叙述，语气比较文雅；日常口语中更常说 turn red 或 go red。它既可表示“变红”，也可表示“使变红”，使用时注意其偏书面的语体色彩。
hidden, ridden, and forbidden all contain the stressed sound /ɪdən/, so they rhyme with one another; none of them rhymes with redden /ˈrɛdən/. sadden /ˈsædən/, sudden /ˈsʌdən/, and trodden /ˈtrɒdən/ are spelling lookalikes with different vowels. redden’s stressed syllable has the /ɛ/ of 'bed', so its closest sound match is 'red' /rɛd/, not the -dden words listed here.
Dictionary facts from ECDICT, WIKTIONARY.