英语听力文摘 English Digest 277、孔隙
时间：2019-03-09 作者：英语课 分类：英语听力文摘 English Digest
Sugar bowls and hole
孔隙是岩土固体矿物颗粒间的空间。岩土中直径大于1毫米、重力水可于其中自由运动的孔隙，是大孔隙（macro-pore，large pore）。岩土中直径为0.01～1毫米、重力水和毛管水可存其中的孔隙，是小孔隙（small pore）。岩土中直径为0.1～10微米、无重力水但毛管现象明显的孔隙，是微孔隙（micropore)。岩土中直径为0.1微米～1毫米、具毛管特性的孔隙，称毛管孔隙（capillary pore）。粘性土中直径小于0.1微米、充满结合水的孔隙，是超微孔隙（ultramicropore），又称超毛管孔隙（uhracapillarypore）。
If you’ve ever had to dig a hole and then fill it back in, you may have noticed a mysterious thing: there was always a little dirt left over. This can often be seen when construction crews(施工员) dig down to get at sewer 1 pipes(污水管) or electric cables(电缆). But how can there be more dirt going in than there was coming out?
The answer is that the amount of soil itself remains 2 the same; what has changed is the arrangement of the individual grains. To see how this happens, think of a sugar bowl. If every crystal of sugar is evenly spaced, the ratio of crystals to empty space will be 60 – 40. That’s true no matter how big the bowl: 40% of the inside will always be empty.
Now put a spoon in and smooth the surface of the sugar: all those evenly-spaced crystals will be packed down into an uneven 3 arrangement, filling the empty spaces. The result is still a 60 – 40 ratio, only now we have a lower level of sugar, with the empty space (1)moved up top.
It’s the same with soil. Rainwater and passing feet press the soil down so that the grains lie closely together with little empty space, called “pore space(孔隙).” When the shovel 4 pulls the soil up and scatters 5 it in a big pile, the soil grains fall down into a pattern closer to the way they were before being packed down. Once the hole is refilled, all you have to do to make it level is get rid of that pore space — which can be easily done with the back of a shovel.
Notes:
(1)move up提升，上升；向前移动
- They are tearing up the street to repair a sewer. 他们正挖开马路修下水道。
- The boy kicked a stone into the sewer. 那个男孩把一石子踢进了下水道。
- He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
- The remains of the meal were fed to the dog.残羹剩饭喂狗了。
- The sidewalk is very uneven—be careful where you walk.这人行道凹凸不平—走路时请小心。
- The country was noted for its uneven distribution of land resources.这个国家以土地资源分布不均匀出名。
- He was working with a pick and shovel.他在用镐和铲干活。
- He seized a shovel and set to.他拿起一把铲就干上了。