Grimm's major contribution to historical linguistics is his explanation of the relationships among cognates in terms of a sound shift, the systematic modification of a series of phonemes.

格里姆对历史语言学的主要贡献是，他从音变-一系列音位有系统的变异-的角度解释了同源词之间的关系。

The shift from silent to sound film at the end of the 1920s marks, so far, the most important transformation in motion picture history.

20世纪20年代末无声电影向有声电影的转变标志着迄今为止电影史上最重要的转变。

It may sound silly, but even the tiniest shift of a kitchen table or couch can make all the difference.

听起来可能很傻，但是即使最小的移动厨房的桌子或者椅子都可以有很大的改变。

It is similar to how the sound of a train's whistle seems to shift as it recedes into the distance.

这个现象与当火车向远处后退时的汽笛响声类似。