After a series of expansions and contractions, they blow off their outer layers, become white dwarfs, and fade away over billions of years.

经过一系列的膨胀和收缩，它们的外层被吹散，变成白矮星，并在数十亿年的时间里逐渐消失。

It has also very low thermal expansion, so expansion and contraction are minimized, reducing the thermal stress in the aircraft.

它还具有非常低的热膨胀，因此膨胀和收缩最小化，从而减少了飞机中的热应力。

As the structures are not closed off like a ring would be, they allow for expansion and contraction of the trachea when we breathe.

因为这些结构并没有像戒指一样完全封闭，在呼吸时它们允许气管的扩张和收缩。

And the fact that it was always on reduced the thermal cycling of the filament and components limiting the stress caused by thermal expansion and contraction.

而且它始终处于开启状态可减少灯丝和组件的热循环，从而限制由热膨胀和收缩引起的应力。