【正文】 to burn waste material lying about, but such burning destroys the useful matter in the dead plants. Although the ashes that are left are valuable when put on the land, a better practice is to bury the waste so that it decays and increases the humus in the soil. In the past, when the world population was much lower than it is now, a man had little difficulty in ordinary times in growing the food that was needed. When a field had been used some years and had bee tired, the farmer could move to another place. The tired land then slowly recovered. Gradually grasses and other plants would appear on it and its productive power would slowly return to normal through their decay. But nature, left alone, would take a long time to bring back the land to its former state。 1 閱讀理解訓(xùn)練題 （十四） A Friend is better than fortune. Friend is worse than poison in some cases. The two sentences above are opposite and seem to be unreasonable but they can be explained as follows: the first refers to all good friends who drive us towards good while the second all bad ones who lead us to wrong ways. My ideal(理想的 ) friend is of course a good friend whose goodness is shown belowhe has no bad likings, such as smoking and drinking. He lives in frugality(節(jié)儉 ). He studies hard so as not to waste his golden time. At home he honors his parents and loves his brothers。 the length of time required would depend on local conditions, but it might well be ten years. It is a bad practice to grow the same crop in a field year after year. If the crop is changed, the land will suffer less because it is treated and used in a different way. Different plants have different effects on the soil. Therefore, a change of crop will do less harm than the growing of the same crop year after year and a regular change to grass will do good to the soil. Much will therefore be gained if different crops are grown one after another, a method known as the rotation(輪作 ) of crops. 72. According to the passage, the land will bee poorer A. if all the dead leaves are cleared away B. if the humus is increased after the harvest C. if dead leaves decay in the soil by themselves D. if waste plant material lying about is buried 73. We can learn from the passage that the tired land has gradually recovered