Testing new-model plane is a （） job, but he decided to devote himself to it.

As automobiles, trucks, buses, and aircraft of all sorts came into use, each with internal combustion engines, the demand for petroleum zoomed upward. Houses began to be heated by burning fuel oil rather than coal. Ships began to use oil; electricity began to be formed from the energy of burning oil.
In 1900, the energy derived from burning petroleum was only 4 percent that of coal. After World War II , the energy derived from burning the various fractions of petroleum exceeded that of coal, and petroleum is not the chief fuel powering the world’s technology.
The greater convenience of petroleum as compared with coal is, however, balanced by the fact that petroleum exist on Earth in far smaller quantities than coal does. (This is not surprising, since the fatty substances from which petroleum was formed are far less common on Earth than the woody substances from which coal was formed.)
The total quantity of petroleum now thought to exist on Earth is about 14 trillion gallons. In weight that is only one-ninth as much as the total existing quantity of coal and, at the present moment, petroleum is being used up much more quickly. At the present rate of the use, the world’s supply of petroleum may last for only thirty years or so.
There is another complication in the fact that petroleum is not nearly so evenly distributed as coal is. The major consumers of energy have enough local coal to keep going but are, however, seriously short of petroleum. The United Stated has 10 percent of the total petroleum reserves of the world in its own territory, and has been a major producer for decades. It still is, but its enormous consumption of petroleum products is now making it an oil importer, so that it is increasingly dependent on foreign nations for this vital resource. The Soviet Union has about as much petroleum as the United States, but it uses less, so it can be an exporter.
Nearly three-fifths of all known petroleum reserves on Earth is to be found in the territory of the various Arabic-speaking countries. Kuwait, for instance, which is a small nation at the head of the Persian Gulf, with an area only three-fourths that of Massachusetts and a population of about half a million, possesses about one-fifth of all the known petroleum reserves in the world.
The political problems this creates are already becoming crucial.

As automobiles, trucks, buses, and aircraft of all sorts came into use, each with internal combustion engines, the demand for petroleum zoomed upward. Houses began to be heated by burning fuel oil rather than coal. Ships began to use oil; electricity began to be formed from the energy of burning oil.
In 1900, the energy derived from burning petroleum was only 4 percent that of coal. After World War II , the energy derived from burning the various fractions of petroleum exceeded that of coal, and petroleum is not the chief fuel powering the world’s technology.
The greater convenience of petroleum as compared with coal is, however, balanced by the fact that petroleum exist on Earth in far smaller quantities than coal does. (This is not surprising, since the fatty substances from which petroleum was formed are far less common on Earth than the woody substances from which coal was formed.)
The total quantity of petroleum now thought to exist on Earth is about 14 trillion gallons. In weight that is only one-ninth as much as the total existing quantity of coal and, at the present moment, petroleum is being used up much more quickly. At the present rate of the use, the world’s supply of petroleum may last for only thirty years or so.
There is another complication in the fact that petroleum is not nearly so evenly distributed as coal is. The major consumers of energy have enough local coal to keep going but are, however, seriously short of petroleum. The United Stated has 10 percent of the total petroleum reserves of the world in its own territory, and has been a major producer for decades. It still is, but its enormous consumption of petroleum products is now making it an oil importer, so that it is increasingly dependent on foreign nations for this vital resource. The Soviet Union has about as much petroleum as the United States, but it uses less, so it can be an exporter.
Nearly three-fifths of all known petroleum reserves on Earth is to be found in the territory of the various Arabic-speaking countries. Kuwait, for instance, which is a small nation at the head of the Persian Gulf, with an area only three-fourths that of Massachusetts and a population of about half a million, possesses about one-fifth of all the known petroleum reserves in the world.
The political problems this creates are already becoming crucial.