酸腐蚀钢，而混凝土中有一种碱性化学反应，可以中和酸化作用。
304. Aluminum beams have already been used for bridge construction and for the framework of a few buildings. 铝制梁已在桥梁建筑及一些建筑的框架中使用。
305. Attempts are also made to produce concrete with more strength and durability, and with lighter weight. 现在，人们在尝试生产一些强度更高，使用寿命更长，重量更轻的混凝土。 306. Another advantage is that steel does not rust in concrete. 另外一个优点就是钢筋不会在混凝土中腐蚀。
307. The word ?contract? is derived from the Latin ?contractum?, meaning drawn together. 合同一词来自于拉丁语contractum, 意思是结合在一起。
308. We all enter into contracts almost every day for the supply of goods, transportation and similar service. 我们差不多每天都要处理合同，如供货、运输以及类似服务。
309. A contract has been defined as an agreement which creates and contemplates an obligation. 订立合同就是达成有关责任和义务的协议。
310. In general, English law requires no special formalities in making contracts. 一般来说，按照英国法律，订立合同并不需要特殊的手续。
311. The contract terms are set out in writing in a document. 合同条款写成书面文件。 312. Thus by setting down the terms of a contract in writing one secures avoiding disputes. 这样，把合同条款写下来以避免发生争议。
313. The contractor is not entitled to receive payment in full until the work is satisfactorily completed. 在工程没有达到满意地完成以前，承包人得不到全部应付款。
314. The employer or promoter of civil engineering works normally determines the conditions of contract. 通常由土木工程的发包人确定合同条款。
315. The employer is entitled to know the reasoning underlying the engineer?s choice of contract. 业主有权了解工程师在选择合同时所根据的理由。
316. Construction plans and specifications stipulate many requirements that are to be met by materials or construction procedures. 施工图纸和规范规定了材料或施工过程应该满足的许多要求。
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317. There are two basically different control procedures for assuring a specified embankment density. 确保规定的路堤密度有两种不同的基本控制步骤。
318. The accepted procedure is to remove practically all vegetable matter from the original ground and from fill material. 采用的方法是从原地面和填料中清除几乎全部的植物。
319. The second procedure is to state the manner and method for constructing the embankment. 第二个步骤是叙述铺筑路堤的方式和方法。
320. Layered construction also produced greater uniformity in the material itself and in its density and moisture content. 分层施工能得到更好的密度、含水量以及材料本身的均匀性。 321. Selective clearing in adjoining areas may at times be required. 在需要的时候，在道路的连接处，进行一些有选择的清理是有必要的。
322. Clearing site sometimes can involve removing trees and tree stumps and disposing of the debris. 清理场地有时包括搬移树、树桩和处理碎屑。
323. The vehicles involved in all crashes, 5% were reported defective and 8% were so reported in fatal accidents. 据报告，在所有撞车事故中，5%的车辆存在缺陷，8%的涉及死亡事故的车辆也是有缺陷的。
324. The advent of high speed divided roads has created an additional problem for the road surface in wet weather. 分道行驶的高速公路的出现，对于雨天的道路表面带来了新问题。 325. The actual degree of safety one experiences on a given highway is determined by decisions made on many different levels. 在某条高速公路上所感受到的真实安全度，是由许多不同的影响安全的因素决定的。
326. Safe highways are expensive and it appears that the driving public does not want safe highways. 安全的高速公路造价昂贵，而看起来驾驶员也并不喜欢安全的高速公路。 327. Therefore, to prevent vehicle malfunction, mandatory motor vehicle inspection programs are being enforced. 因此，为了避免车辆发生故障，机动车辆检查项目是强制实施的。 328. Therefore, highway improvement is also a key factor in preventing accidents. 因此，高速公路的改进也是避免交通事故发生的关键因素。
329. Building it is the first step in producing a finished facility. 建筑路基是提供完美公路设施的
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第一步。
330. The collapse of the Tacoma Narrow Bridge was the result of not considering the last these factors. Tacoma Narrows桥倒塌是由于没有考虑到这些因素中的最后一个。
五．汉译英题：
331. 这些伟大建筑物不是数学知识和物理知识的产物。反而它们修建在经验和观察的基础之上，经常是作为反复试验不断摸索的结果。它们幸存下来的原因之一就是建筑于其内的巨大强度—在大部分情况下这种强度比必要的强度要大得多。These great buildings were not the product of knowledge of mathematics and physics. They were constructed instead on the basis of experience and observation, often as the result of trial and error. One of the reasons they have survived is because of the great strength that was built in them—strength more than necessary in most cases.
332. 人们可以利用好几种电子测距仪。这些仪器的优点稍有不同，但是它们的工作原理是
相同的。它们主要由一个安装在被测距离一端的发射器和一个安装在另一端的发射器组成。Several EDM devices are available. They have slightly different advantages, but they all work on the same general principle. They consist mainly of a transmitter located at one end of distance to be measured and a reflector at the other end.
333. 混凝土受压时表现很强，但是受拉时表现很弱。它的抗拉强度只有它抗压强度的百分
之八到百分之十四。由于这样低的抗拉能力，在它的荷载早期就会形成弯曲的裂缝。Concrete is strong in compression, but weak in tension. Its tensile strength varies from 8 to 14 percent of its compressive strength. Due to such a low tensile capacity, flexural cracks develop at early stages of loading.
334. 排水设施根据水来源的不同可分为两种类型，地面排水设施和地下排水设施。公路的
地面排水系统包括足够大的横坡和纵坡、纵向沟渠、涵洞、桥梁以及设置在分向行驶公路中间带上的雨水井与排水管。地下排水系统排除三种形式的水：通过裂缝或接缝的渗透水、毛细作用上升水以及地下水。Drainage facilities are divided into two types according
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to the water sources, surface and subsurface drainage. The surface drainage system for highways include sufficient transverse and longitudinal slopes, longitudinal channels, culverts, bridges and storm inlets and drains, which are provided on the median of divided highways. Subsurface drainage system drains water in three forms: water that has permeated through cracks and joints, water that has moved upward as a result of capillary action and ground water.
335. 公路定线包括现有资料的室内研究、路线踏勘测量、初步定线和最终定线。踏勘测量的
主要任务是在路线带内确定几条可行的路线，并把它绘在地图上。近来，计算机技术的应用极大地提高了公路定线的效率，从而使得到最佳路线成为可能。The highway location involves four phases: office study of existing information, reconnaissance survey of routes] preliminary location and final location. The primary object of reconnaissance survey is to identify several feasible routes with a band, then plotting on photographic maps.
336. 坡度对于卡车比对客车有更大的影响。最大纵坡的选择取决于设计车速和设计车辆，
最小纵坡则取决于公路的排水状况。建在有适当路拱、坚实的地基上的高级路面，其最小纵坡可以减小到0.3%。Grade has a greater impact on trucks than passenger cars. The selection of maximum grade for a highway depends on design speed and design vehicle, and that of minimum grade depends on the drainage conditions of the highway. Minimum grade maybe reduced to 0.3 percent on high-type pavement constructed on suitably crowned, firm ground.
337. 城市平面交叉口通常需要采用信号控制来组织交通及减少事故。在立交中，车辆通过
匝道来转换行驶方向。设计菱形立交匝道时，必须注意避免错路运行。In urban areas, the intersections at grade generally require signalized control to organize the vehicles and decrease in accidents. The vehicles in interchange may transfer their movement direction by the use of ramps. Wrong-way movements must be taken care of in the design of the ramps of diamond interchange.
338. 按照设计标准修建的高速公路是各种等级公路中最安全的。据估计，高速公路承担着
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