When you're driving in your car, there's a needle and the needle says 60; that's your velocity at this instant.

当你在开车时,有一根指针指着60,表示你这个时刻的速度

耶鲁公开课 - 基础物理课程节选

it's like finding a needle in a hay stack.

这简直是大海捞针。

It's like 课堂 - SpeakingMax英语口语达人

It involves putting a needle, a fairly large needle into usually one of the pelvic bones and collecting marrow from which is tissue that's deep inside those bones.

先要用针头,相当大的针头刺进你的盆骨,然后进行收集,这些在骨头深处的骨髓

耶鲁公开课 - 生物医学工程探索课程节选

This spring is getting squashed on either side, and it'll squash by certain amount x, that depends on your mass, and that x will be turned into a motion of a needle and that'll read your mass.

这个弹簧两边都会受到压缩,压缩量为 x,它由你的质量决定,x 会转换成指针的运动,你从而可以读数

耶鲁公开课 - 基础物理课程节选