WHICH OF THE FOLLOWING BEST EXPRESSES THE ESSENTIAL INFORMATION IN TH...

Câu 42: Which of the following best expresses the essential information in the

highlighted sentence in the passage?

A. The habitable zones of small stars are so close to the star that planets within them do not

spin.

B. Because of their nearness, habitable planets orbiting smaller stars usually have

either constant daylight or constant night.

C. One problem with some stars is that their habitable zones are tidally locked into

either light or darkness.

D. Some stars become tidally locked, so that they only shine light on one side of a planet.

Read the following passage and mark the letter A, B, C or D on your answer sheet to

indicate the correct answer to each of the questions.

Today we take electricity for granted and perhaps we do not realize just how useful this

discovery has been. Steam was the first invention that replaced wind power. It was used to

drive engines and was passed through pipes and radiators to warm rooms. Petrol mixed with

air was the next invention that provided power. Exploded in a cylinder, it drove a motor

engine. Beyond these simple and direct uses, those forms have not much adaptability. On

the other hand, we make use of electricity in thousands of ways. From the powerful voltages

that drive our electric trains to the tiny current needed to work in a simple calculator, and

from the huge electric magnet in steel works that can lift 10 tons to the tiny electric magnet

in a doorbell, all are powered by electricity. An electric current can be made with equal

ease to heat the huge mass of molten metal in a furnace, or to boil a jug for a cup of coffee.

Other than atomic energy, which has not as yet been harnessed to the full, electricity is the

greatest power in the world. It is flexible, and so adaptable for any task for which it is

wanted. It travels so easily and with incredible speed along wires or conductors that it can

be supplied instantly over vast distances. To generate electricity, huge turbines or

generators must be turned. In Australia, they use coal or water to drive this machinery.

When dams are built, falling water is used to drive the turbines without polluting the

atmosphere with smoke from coal. Atomic power is used in several countries but there is

always fear of an accident. A tragedy once occurred at Chernobyl, in Ukraine, at an atomic

power plant used to make electricity. The reactor leaked, which caused many deaths

through radiation.

Now scientists are examining new ways of creating electricity without harmful effects

to the environment. They may harness the tides as they flow in and out of bays. Most

importantly, they hope to trap sunlight more efficiently. We do use solar heaters for

swimming pools but as yet improvement in the capacity of the solar cells to create more

current is necessary. When this happens, electric cars will be viable and the world will rid

itself of the toxic gases given off by trucks and cars that burn fossil fuels.