Water problems in the future will become intense and more complex. On the one hand, our increasing population will tremendously increase urban wastes, primarily sewage. On the other hand, rapidly expanding industries which involve more complex chemical processes will produce larger volumes of liquid wastes, and many of these will contain chemicals which are noxious. To feed our rapidly expanding population, agriculture will have to be intensified. This will involve ever-increasing quantities of agricultural chemicals. From this, it is apparent that drastic steps must be taken immediately to develop corrective measures for the pollution problem.
There are two ways by which this pollution problem can be dwindled. The first relates to treatment of wastes to decrease their pollution hazard. This involves the processing of solid wastes "prior to" disposal and the treatment of liquid wastes, or effluents, to permit the reuse of the water or minimize pollution upon final disposal.
A second approach is to develop an economic use for all or a part of the wastes. Farm manure is spread in fields as a nutrient or organic supplement. Effluents from sewage disposal plants are used in some areas both for irrigation and for the nutrient supplement contained. Effluents from other processing plants may also be used as a supplemental source of water. Many industries, such as meat and poultry processing plants, are currently converting former waste products into marketable byproducts. Other industries are exploring potential economic uses for their waste products.

问答题Petroleum is essentially a nonrenewable natural resource, an almost useless mixture comprised of very useful substances. It exists underground in liquid, solid, semisolid, and gaseous states. The name petroleum is derived from the Latin words petra and oleum, meaning rock oil . Created only by nature but exploited by man, petroleum is a nonrenewable resource because people consume it approximately one million times faster than nature can create it. Timber is a renewable natural resource; it can be harvested, replanted, and then reharvested in a few decades. In a sense, petroleum seeds are being planted today because the natural processes that create petroleum occur continuously. However, the results cannot be harvested for many millions of years. The petroleum that man harvests today was planted 30-6,000 million years ago! That is why petroleum is considered nonrenewable.

问答题Today’s policemen in large cities throughout the world rely on modem inventions to help them in their work. In most places motor scooters and police patrol cars have done away with the need to patrol on foot or on horseback. Policemen use telephones, conveniently located throughout their districts, to make immediate contact with headquarters. Radio, television, and computers help to speed the work of the modem force. Even boats and helicopters are part of the equipment of metropolitan police departments. New technical inventions are widely used to fight crime and speed the solution for criminal cases. Electronic computer reduce from hours to minutes the time spent in searching for fingerprints. Witness’s descriptions of a criminal are coded and fed into a computer. The machine then sorts through the picture file of known criminals and selects the name and photograph of the most likely suspect. Lie detectors are used to uncover the truth.

问答题那就是白杨树，西北极普通的一种树，然而实在不是平凡的一种树! 那是一种力争上游的一种树，笔直的干，笔直的枝。它的干呢，通常是丈把高，像是加过人工似的，一丈以内，绝无旁枝：它所有的丫枝呢，一律向上，而且紧紧靠拢，也像是加过人工似的，成为一束，绝无横斜逸出；它的宽大的叶子也是片片向上，几乎没有斜生的，更不用说倒垂了；它的皮，光滑而有银色的晕圈，微微泛出淡青色。这是虽在北方的风雪的压迫下却保持着倔强挺立的一种树!哪怕只有碗来精细罢，它却努力向上发展，高到丈许，二丈，参天耸立，不折不挠，对抗着西北风。

问答题中华民族历来尊重人的尊严和价值。还在遥远的古代，我们的先人就已提出“民为责”的思想，认为“天生万物，唯人为贵”，一切社会的发展和进步，都取决于人的发展和进步，取决于人的尊严的维护和价值的发挥。中国共产党领导人民进行革命、建设和改革，就是要确保全中国人民获得广泛的自由、民主和人权。今天中国所焕发出来的巨大活力，是中国人民拥有广泛自由、民主的生动写照。

问答题由小学到中学，所修习的无非是一些普通的基本知识。就是大学四年，所授课业也还是相当粗浅的学识。世人常称大学为“最高学府”，这名称易滋误解，好像过此以上即无学问可言。大学的研究所才是初步研究学问的所在，在这里做学问也只能算是粗涉藩篱，注重的是研究学问的方法与实习。学无止境，一生的时间都嫌太短，所以古人皓首穷经，头发白了还是在继续研究，不过在这样的研究中确是有浓厚的趣味。