【英语时差8,16】升华

Another pop quiz coming up on today's Moment of Science. Pop quiz! Everybody put away your books. You fill the ice tray up to the rim¹ and put it in the freezer. The ice that results will be a.) at the rim b.) over the rim c.) under the rim. Answer? It depends. I know, you hate that. But it does depend -- it depends on how long you wait before checking on the ice again. My guess would be that most folks chose answer b: over the rim. That is correct, if you checked on the ice trays after only a couple hours. That's because water expands when it turns into ice, as you know if you ever put a soda² bottle in the freezer and came back to find it exploded all over the fish sticks. But if you were to leave the ice tray untouched for a couple of months, you might find the ice to be under the rim, or lower than the water was. Huh? Didn't we just say water expands when it freezes? Initially³, yes. But frozen water can do something else as well: it can sublimate⁴. To sublimate is to go from one state to another without passing through the usual intermediary state. By adding heat, ice can be melted into liquid water, which can be evaporated. That's three states: solid, liquid, gas. But given enough time, ice can also turn into a gas without melting first! When your ice cubes seem to have shrunk, it's because they are sublimating⁵: the frozen water is slowly evaporating off the cubes, without ever actually melting. Will this work in any freezer? Next time.

1 rim   

n.(圆物的)边，轮缘；边界

参考例句：

• The water was even with the rim of the basin.盆里的水与盆边平齐了。
• She looked at him over the rim of her glass.她的目光越过玻璃杯的边沿看着他。

2 soda   

n.苏打水；汽水

参考例句：

• She doesn't enjoy drinking chocolate soda.她不喜欢喝巧克力汽水。
• I will freshen your drink with more soda and ice cubes.我给你的饮料重加一些苏打水和冰块。

3 initially   

adv.最初，开始

参考例句：

• The ban was initially opposed by the US.这一禁令首先遭到美国的反对。
• Feathers initially developed from insect scales.羽毛最初由昆虫的翅瓣演化而来。

4 sublimate   

v.(使)升华，净化

参考例句：

• We need sublimate water for our experiment.我们的实验需要纯净化的水。
• Her sublimate future husband will be tall,dark,and handsome.她理想化的未来丈夫将是身材高大，皮肤浅黑，相貌英俊。

5 sublimating   

v.（使某物质）升华( sublimate的现在分词 )；使净化；纯化

参考例句：