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a crocus
crocus 是可数名词，指单株植物时通常用 a/an。
A purple crocus was blooming in the snow.
一朵紫色的番红花在雪中绽放。
番红花
先理解核心含义，再看它在真实句子里的用法。
番红花
a small plant of the genus Crocus with slender, grasslike leaves and white, yellow, or purple flowers, native mainly to the Mediterranean region and widely cultivated
A purple crocus was blooming in the snow.
一朵紫色的番红花在雪中绽放。
鸢尾科番红花属多年生开花植物,藏红花取自番红花(Crocus sativus)的雄蕊。
A perennial flowering plant (of the genus Crocus in the Iridaceae family). Saffron is obtained from the stamens of Crocus sativus.
各种类似的开花植物,如秋水仙和草原番红花。
Any of various similar flowering plants, such as autumn crocus and prairie crocus.
The first crocus bloomed in the garden in late February.
二月底，花园里第一朵番红花开了。
We planted crocuses along the path so they would flower in early spring.
我们在小路边种了番红花，让它们在早春开花。
A cluster of purple crocuses appeared under the old tree.
老树下出现了一丛紫色的番红花。
crocus 是可数名词，指单株植物时通常用 a/an。
A purple crocus was blooming in the snow.
一朵紫色的番红花在雪中绽放。
复数形式常用 crocuses，也可写作 croci。
These crocuses bloom in early spring.
这些番红花在早春开花。
表示“种植番红花”时，crocuses 作 plant 的宾语。
We planted crocuses along the garden path.
我们在花园小径旁种了番红花。
Not this
I saw crocus blooming in the garden.
Use this
I saw a crocus blooming in the garden.
crocus 是可数名词单数，单独使用时必须加限定词（如 a / the / this）。中文没有冠词，所以容易漏掉 a；加上 a 后句子才符合英语单数可数名词的用法。
Not this
There are many crocus in the garden.
Use this
There are many crocuses in the garden.
crocus 的复数形式是 crocuses（较少用 croci），不能像 sheep 那样单复同形。many 后要用复数名词，所以要把 crocus 改为 crocuses。
Focus on the distinctions below. Other candidates are kept compact until a reliable usage note is available.
春季番红花
The first spring crocus appeared in late February.
第一朵春季番红花在二月底开放。
番红花球根
Plant the crocus bulbs in a sunny spot.
把番红花球根种在阳光充足的地方。
藏红花（一种番红花）
The saffron crocus blooms in autumn, not spring.
藏红花在秋天开花，不是在春天。
紫色番红花
Purple crocuses covered the lawn.
紫色的番红花开满了草坪。
种植番红花
We planted crocuses under the apple tree.
我们在苹果树下种了番红花。
Use crocus naturally, then get feedback on meaning, tone, grammar, and phrasing.
Revisit a common error or keep this word in your review list.
联想：番红花crocus，读作‘克罗克斯’，细长叶间紫花像丝线。
语域：neutral 常见场景：gardening、botany、nature writing crocus 是常见的植物名称，通常用于园艺、植物学描述或日常谈论春季花卉。多用于中性语境，既不算口语也不算正式。
与 focus、locus 同韵：重读元音及之后均为 /əukəs/（美式常读 /oʊ-/）。注意 crocodile /ˈkrɒkədaɪl/ 开头同为 cro- 但不押韵；circus /ˈsɜːkəs/ 结尾同为 -cus，但元音和重音不同。
Dictionary facts from ECDICT, WIKTIONARY.