He suffered a hairline fracture of the right index finger.

他的右手食指上出现一处丝状骨折。

Wrap a rubber band from your index finger to your pinky and move your index finger away from the other fingers.

把你的食指和小指用橡皮筋绑在一起，然后把食指从其他手指间移开。

Why with thumb and index finger?

为什么要拇指和食指一起？

Left index finger: single.

左手食指：未婚。

The index finger towardS the interior of S.

食指指向s的内侧。