食指的英文：
forefinger
index finger
pointer finger

the apposition of thumb and forefinger
大拇指与食指并列

The little child took her ear between her thumb and forefinger and tugged it playfully.
小孩用大拇指和食指捏住她的耳朵，拉着玩。

His hand went into his pocket and a forefinger felt its way under the flap of the envelope, ripping it open in jerks
他把手伸进兜里，一只食指摸索到信封的口盖，分几截把信扯开了。

The thumb is opposable to the forefinger.
大姆指可与食指相对。

His finger has swelled up.
他的食指肿起来了。

To shoot(a marble)with the thumb over the bent forefinger.
弹玻璃弹子拇指在弯曲的食指上方射出(弹子)

The competitor's fingers shall be outside the trigger guard while reloading.
因此在重新装填弹药时选手的食指一定要置于扳机护弓之外。

With your right hand lightly grasp the grip and place your index finger lightly over the shutter button.
用您的右手轻轻握住相机手柄，并把您的食指轻轻地放在快门按钮上。

You distance all rivals, and may soon touch the sky with your forefinger
你把一切敌手都远远抛在后面，不久就能用你的食指触着天了。

Also, Americans often indicate "OK" with their thumb and forefinger touching to form a circle
还有，美国人通常用大拇指及食指环绕起一个圆圈表示「没问题」。

He held it between the tips of his thumb and forefinger.
他用他大拇指和食指尖拿着它。

He hold it between the tips of his thumb and forefinger.
他用大拇指和食指尖拿著它。

To shoot(a marble)with the thumb over the bent forefinger.
弹玻璃弹子拇指在弯曲的食指上方射出(弹子)

The simplest form of a composite index is an unweighted aggregates index
综合指数最简单的形式是不加权数的总计指数。

Social Sciences Citation Index
社会科学引文索引

The radius represents the advancement index.
辐枝代表进化指数。