Don't hold unnecessary tension in your face or jaw, in your neck or shoulders.

不要给你的脸颊和下巴带来不必要的紧张，放松你的脖子和肩膀。

youdao

Thus, while using this mouse hand of man will be in a really comfortable position that will help to avoid unnecessary effort and tension in the joints during manipulation.

因此，使用这种鼠标的人，手得到一个非常舒适的位置，可避免操作中手关节上不必要的紧张。

youdao

Can be added to resolve, add to the belt does not slip until, but can not add too much, so as not to make the belt to bear unnecessary excessive tension and reduce the life of the belt.

可添加配重来解决，添加到皮带不打滑为止，但不能添加太多，以免使皮带承受不必要的过大张力而降低皮带的使用寿命。

youdao

There was always unnecessary tension, unnecessary intimidation.

WSJ: Mercurial Charles Mingus | Mingus Ah Um | Masterpiece by Eric Felten

The statement from his office on Thursday called on the court to cease pursuing him and to abide by the rule of law - "the absence of which will cause mockery of the nation... unnecessary tension amongst the various pillars of state and possibly destabilize the country".

BBC: Asia