Dung is in constant supply wherever there are farm animals and, when dried, it is convenient to store and use. But burning dung destroys its values as fertilizer, thus depriving the soil of the much needed source of humus and nitrogen.
Rural areas of developing countries are also plagued by a lack of adequate sanitation. Improper waste disposal spreads disease, contaminates water sources and provides breeding ground for diseases-carrying insects.
The problem of improving environmental hygiene, conserving resources, and finding alternative sources of fuel may be unrelated. Their solutions, however, are not, as many countries experimenting with biogas technology are discovering. Biogas, a mixture of methane and carbon dioxide, is produced by the fermentation of organic matter. The process of anaerobic fermentation is a natural one, occurring when every living matter decomposes. By keeping the matter, – and the process – in a digester or biogas plant the combustible gas can be trapped and used as fuel for household lighting and cooking. The digested slurry that remains can be used on the land as a soil conditioner and fertilizer.
(A) pollution and the high price of fuel
(B) widespread deforestation and the use of dung
(C) the lack of adequate fuel and hygienic condition
(D) the lack of humus and nitrogen in the soil
(E) contaminated water sources and rural areas
(B) are difficult to extract
(C) make the soil poor
(D) do not meet people needs
(E) cause damage to the environment
(B) the pollution of water sources
(C) the great number farm animal
(D) the badly managed waste disposal
(E) the increase of disease- carrying insects
04. What is the text mainly about?
(B) The process of producing biogas.
(C) The effect of burning dung on the soil.
(D) Biogas as a solution to many problems.
(E) The disadvantages of using dung as fuel.
05. As an inexhaustible source of energy, the sun will never stop shining.
(A) never used up completely
(B) easy to get burned
(C) reduce quickly
(D) wasted easily