沟渠

"But stone in compression has great strength, and the Romans built huge stone bridge s and aqueducts."

但是石头在压力下具有良好的强度，并且，罗马人建造了巨大的石头桥梁与沟渠。

Roman engineers maintained water levels in aqueducts by means of float ing valves that opened and closed at appropriate levels.

罗马工程师用在适当水位开、关的浮子式阀来保持沟渠系统的水位。

The aqueducts which had supplied the city with water for more than 1000 years were allowed to become obstructed and fall into disrepair.

城市供水之用的沟渠一千多年来，变成了一种阻塞，并且陷入失修。

Most people think of concrete as a modern material,but its history begins with the Romans,who used it to build their aqueducts and amphitheaters.

许多人把混凝土想成一个现代的产物，然而，它却始于罗马时代。罗马人用它来建造沟渠，建造竞技场。

The results indicated that the transfer and loss of N and P vary with means of rotation, types of crops and the amount of fertilizer application. Buffering forest belts betweens farmlands and ditches can effectively stop and purify such elements as N and P in soil runoffs, thus controlling non-point source pollution of agricultural lands.

结果表明：农田生态系统中 N、P等迁移、淋失状况随轮作方式、作物种类及施肥状况而变化；农田与沟渠间的缓冲林带具有截留和净化土壤径流中的N、P等物质的作用，从而在一定程度上控制农业非点源污染。

The deserted buildings of the residential district were torn down, but their colonnades were retained and arranged into a waterfall by having water pass over them as in the Roman aqueducts.

废弃的住宅区建筑被拆除，但其间的柱廊却保留着，瀑布从它们之间流过，就象罗马用来排水的沟渠。

Is the area free of hazards such as culverts, drainage ditches, and open sewers?

是该地区自由的危险，如涵洞，排水沟渠，并打开下水道？

Ditches and drainages should be dredged regularly.

沟渠和排水道要定期疏浚。

There has been various large-scale dredgers used for broad rivers, and the technique is already very mature, but producing such a dredger costs more than ten millions. In addition, they can only be applied to large-scale fields. it's incapable for narrower fields, such as pools and ditches in suburbs, the corners of dike and so on.

世界上已有的用于大型江河湖泊清淤的各种不同的挖泥船技术已经相当成熟，但制造这样一艘挖泥船所需成本高达上千万，而且它只能应用于作用面积极大的场合，对于水域狭窄的郊区、农村的沟渠、池塘和溪流以及堤岸死角等处的清淤就爱莫能助了。

The topographic features of a region include both natural (hills, canals, oceans, rivers, lakes, and foliages) and manmade (cities, bridges, roads and canals) elements in a region.

一个地区的平流层特征包括自然的（小山，沟渠，海洋，河流，湖泊，植物）和人造的的因素。

However, as the name（read－only memory）implies, CD disks cannot be written onorchanged in any way.

然而，正如其名字所指出的那样，CD盘不能写，也不能用任何方式改变其内容。

Galvanizes steel pallet is mainly export which suits standard packing of European Union, the North America. galvanizes steel pallet is suitable to heavy rack. Pallet surface can design plate type, corrugated and the gap form, satisfies the different requirements.

镀锌钢托盘多用于出口，替代木托盘，免薰蒸，符合欧盟、北美各国对出口货物包装材料的法令要求；喷涂钢托盘适用于重载上货架之用，托盘表面根据需要制作成平板状、波纹状及间隔形式，满足不同的使用要求。