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the forefinger
指称这根手指时常用定冠词 the，表示特指或泛指这一类手指。
The forefinger is the finger next to the thumb.
食指是紧挨着拇指的那根手指。
食指
先理解核心含义，再看它在真实句子里的用法。
食指
the finger next to the thumb
The forefinger is the finger next to the thumb.
食指是紧挨着拇指的那根手指。
The index finger: the first finger next to the thumb.
She pointed at the map with her forefinger.
她用食指指着地图。
He gently touched the button with his forefinger to avoid making a noise.
他轻轻用食指按了一下按钮，以免发出声响。
My forefinger got sore after writing for two hours.
写了两个小时的字后，我的食指酸痛。
指称这根手指时常用定冠词 the，表示特指或泛指这一类手指。
The forefinger is the finger next to the thumb.
食指是紧挨着拇指的那根手指。
用 of 短语说明食指与身体部位或所属者的关系。
The ring was on the forefinger of her left hand.
戒指戴在她左手的食指上。
用 with 引导的介词短语表示“用食指”作为完成动作的工具。
He traced the word with his forefinger.
他用食指描画那个词。
Not this
She pointed at me with forefinger.
Use this
She pointed at me with her forefinger.
forefinger 是可数名词，单数使用时必须有冠词或物主代词等限定词；中文没有冠词，容易漏掉。加上 her 后句子才完整。
Not this
I wear the ring in my forefinger.
Use this
I wear the ring on my forefinger.
表示戒指戴在手指上，英语介词用 on，不用 in；这是中文“在……上”与英语介词搭配不一致导致的错误。
Focus on the distinctions below. Other candidates are kept compact until a reliable usage note is available.
用食指指
He pointed his forefinger at the map.
他用食指指着地图。
在拇指和食指之间
She held the coin between her thumb and forefinger.
她用拇指和食指夹着硬币。
竖起食指
The teacher raised a forefinger to ask for silence.
老师竖起食指示意大家安静。
用食指轻敲
He tapped his forefinger on the table impatiently.
他不耐烦地用食指轻敲桌子。
食指放在扳机上
Keep your forefinger on the trigger only when you are ready to shoot.
只有准备射击时，才把食指放在扳机上。
Use forefinger naturally, then get feedback on meaning, tone, grammar, and phrasing.
Revisit a common error or keep this word in your review list.
fore 是‘前’，forefinger 即拇指旁最靠前的手指，联想数数时用食指指着前方比划。
语域：neutral 常见场景：医学/解剖描述、书面说明或教学中 “forefinger” 意为“食指”，是中性且正式的说法，与 “index finger” 同义；多用于医学、解剖或书面描述，日常口语中更常说 “index finger”。
医学语境中也可称示指。
Dictionary facts from ECDICT, WIKTIONARY.