Read the following article and answer the question. Article: There is very simple way of measuring the height of a water-tower, which we cannot measure by climbing. Suppose, for example, that we wish to find out the height of the water-tower, AB, in a factory. We first of all go to where the water-tower is standing and measure a distance of, say, 25 feet from it. Then we take a stick, and stand it in the ground at the spot we have just marked. Let us suppose the stick we are using is 4 feet in height. We now walk farther away from the water -tower in the same straight line as when we measured off the distance of 25 feet. We go from the water-tower until we come to point E, where with our head on the ground, we see the top of the stick and the top of the water-tower in the same height line---that is, the top of the stick just covers the highest part of the water-tower. Every schoolboy can work out the height of the water-tower now. Suppose that the line CE is five feet. We know that the stick is 4 feet high and the distance BE is 30 feet. Thus, 5 is to 4 as 30 is to AB. Question: To measure a water-tower in this way, _ . Answer:
OPTIONS:
- no tool is needed
- Besides a stick, tape-measure or at least a ruler is necessary.
- we have to use nothing but a stick
- we have to prepare a set of expensive tools

Answer: we have to use nothing but a stick

Read the following article and answer the question. Article: Charles Darwin (1809 - 1882) was a great naturalist, famous for his theory of evolution . One day two boys decided to play a trick on the great man. They took the body of a centipede , the head of a beetle , the leg of a grasshopper , and the wings of a butterfly, and glued them together. Putting the strange creature into a box carefully, they took it to Darwin. "Please, sir," said one of the two boys, "can you tell us what sort of a bug this is?" The naturalist looked at the bug and then at the boys. "Did it hum ?" he asked. "Oh, yes. It did!" "In that case," declared Darwin, "I would say it's a humbug !" Question: When Darwin declared "I would say it's a humbug", he meant that _ . Answer:
OPTIONS:
- the bug was really a humbug
- the bug was indeed a strange bug
- the bug cheated him
- he looked through the boys' trick

Answer: he looked through the boys' trick

Read the following article and answer the question. Article: Solar energy for your home is coming. It can help you as a single home owner. It can help the whole country as well. Whether or not solar energy can save your money depends on many things. Where you live is one factor and the type of home you have is another. Things like insulation , present energy costs, and the type of system you buy are added factors. Using solar energy can help save our precious fuel. As you know, our supplies of oil and gas are very limited. There is just not enough on hand to meet all our future energy needs. Sooner or later Mother Nature will say that's all. The only way we can delay hearing those words is by starting to save energy now and by using other sources, like the sun. We won't have to worry about the sun's running out of energy for another several billion years or so. Besides, the sun doesn't offer as many problems as other energy sources. For example, fossil fuel adds to already high pollution levels. With solar energy, we will still need sources of energy, but we won't need as much. That means we can cut down on our pollution problems. With all these good points, why don't we use more solar power? There are many reasons for this. The biggest reason is money. Until now, it was just not practical for a home owner to put in a solar unit. There were cheaper sources of energy. All that is changing now. Solar costs are starting to equal the costs of oil and electricity. Experts say that gas, oil and electricity prices will continue to rise. The demand for electricity is increasing rapidly. But new power plants will use more gas, oil or coal. Already in some places the supply of electricity is being rationed . Solar energy is now in its infancy . It could soon grow to become a major part of our nation's energy supply. Question: What's this passage mainly about? Answer:
OPTIONS:
- Something about solar energy and pollution.
- Solar energy.
- Energy and pollution.
- Energy and money.

Answer:
Solar energy.