1
a mallard
mallard 是可数名词，指一只时用 a/an。
A mallard landed on the lake.
一只绿头鸭落在湖面上。
绿头鸭
先理解核心含义，再看它在真实句子里的用法。
绿头鸭
mallard
A mallard landed on the lake.
一只绿头鸭落在湖面上。
绿头鸭(Anas platyrhynchos),一种常见而分布广泛的钻水鸭,原产于整个北半球,雄鸟头部呈深绿色。
Anas platyrhynchos, a common and widespread dabbling duck, natively found throughout the Northern Hemisphere, whose male has a distinctive dark green head.
广泛分布的野生淡水鸭,为家鸭的祖先。
wild dabbling duck from which domestic ducks are descended; widely distributed
这种鸟的肉,可作食物。
The meat of this bird, eaten as food.
A mallard was swimming slowly across the pond this morning.
今天早上，一只绿头鸭缓缓地游过池塘。
The children fed the mallards some bread near the lake.
孩子们在湖边给几只绿头鸭喂了一些面包。
We saw a mallard with a shiny green head resting by the river.
我们看见一只绿头鸭，头上有亮绿色的羽毛，正在河边休息。
mallard 是可数名词，指一只时用 a/an。
A mallard landed on the lake.
一只绿头鸭落在湖面上。
复数形式是 mallards，用于指多只。
Mallards are common in city parks.
绿头鸭在城市公园里很常见。
Not this
There are many mallard in the lake.
Use this
There are many mallards in the lake.
mallard 是可数名词，复数是 mallards。汉语说“许多绿头鸭”时名词不带复数标记，所以学习者容易漏掉 -s；表示多只个体时必须用复数形式。
Not this
Mallard is a common wild duck.
Use this
The mallard is a common wild duck.
mallard 是单数可数名词，作主语时不能光秃秃地用一个单数名词，需要加限定词（这里用 The 表示泛指这一类）。汉语“绿头鸭是……”没有冠词，所以学习者容易照搬。
Focus on the distinctions below. Other candidates are kept compact until a reliable usage note is available.
绿头鸭
A mallard duck swam across the lake.
一只绿头鸭游过湖面。
雄绿头鸭
The male mallard has a glossy green head.
雄绿头鸭有光滑的绿色头部。
雌绿头鸭
The female mallard is mostly brown.
雌绿头鸭大多呈棕色。
绿头鸭种群
The mallard population in this wetland is stable.
这片湿地的绿头鸭种群数量稳定。
野生绿头鸭
Wild mallards migrate south in winter.
野生绿头鸭冬季南迁。
Use mallard naturally, then get feedback on meaning, tone, grammar, and phrasing.
Revisit a common error or keep this word in your review list.
mallard 里藏着 mall（购物中心）：想象购物中心旁水塘里游着一只绿头鸭，雄鸭头顶绿色。
语域：neutral 常见场景：鸟类图鉴、日常对话 “mallard”是普通词汇，正式和非正式场合都常用，通常指绿头鸭，即家鸭的野生祖先；在鸟类图鉴或日常对话中都比较常见。
All these words end in -ard and share the unstressed final /ɚd/ sound, but none rhymes with mallard /ˈmælɚd/ because the stressed syllable before -ard is different. Note that mallard’s first vowel is /æ/, not the /ɔː/ of mall /mɔːl/.
Dictionary facts from ECDICT, WIKTIONARY.