In the following passages the numbered gaps indicate missing words. Against each number in the below each passage, five choices are offered in columns lette...

In the following passages the numbered gaps indicate missing words. Against each number in the below each passage, five choices are offered in columns lettered A to E. For each question choose the word that is the most suitable to fill the numbered gap in the passage.
Locusts have from time to time been the cause of terrible -71- of farms. -72- of locusts can, in a few hours, strip vast areas of green and fertile country of all signs of -73-. They are -74- or periodic -75-. After a heavy -76- of an area, they may not reappear for ten or fourteen years. Now that more is known of the life of locusts, there periodic -77- are better understood and consequently more -78-. Scientists now know the regions in which the gregarious phase of locusts may occur, and can even sometimes -79- when an -80- will take place. By modern methods of dusting and -81- the young locusts, such as the -82- can be destroyed on a large -83- before they do much -84-. The D.DT -85- has proved particularly effective.
The main source of -86- to the government is -87-, which can be direct. While the former is based on one's -88- the latter is imposed on goods and -89- and is paid only when these are -90-. Other sources include -91-, such as those paid by mining companies, and sale of -92- for dogs, guns, hotels e.t.c. Another major source is -93-, which is different from others because it has to be repaid. From these and other sources, government is able to raise -94- with which it carries out its -95- which include administration and the -96- of services.
Besides, it is able to control the country's -97- by imposing taxes sometimes to prevent -98- or by altering patterns of -99- through the raising of -100- against certain foreign products.