give off a gas

Researchers discovered that plants infected with a virus give off a gas that activates disease resistance in neighboring plants.

研究人员发现，感染病毒的植物能够发出一种气体；这种气体能在临近植物中激发疾病抗体。

Coral grubbs give off a gas that is lighter than air. This keeps the isles suspended in the sky, but can be a nuisance when attempting to construct buildings.

珊瑚虫会放出一种比空气还轻的气体，这种气体使诸岛悬浮于空中，但对于兴建楼房屋宇却又是阻碍不少。

Active galaxies give off bright radiation from their cores, where gas heats up as it is compressed into a swirling accretion disk encircling the black hole.

活动星系从它们的核部发出明亮的光芒，在那里，气体被加热并压缩成一个漩涡状的圆盘，漩涡的中心便是黑洞。