Read the paragraph and choose the best answer.
Are you looking for a cheap, clean, ............ (1) source of power that doesn’t cause …………(2) or waste natural resources? Look no further than solar energy from our sun. At present, most of our …..……(3) comes from the use of coal and gas, oil or nuclear power. This power could be provided by the sun. One percent of the solar energy that reaches the earth is enough to provide………(4) for the total population. Many countries are already using solar energy. Solar panels are placed on the ……..(5) of our house and the Sun’s (6) ….is used to heat water. The energy can be…………….(7). For a number of days, so on cloudy days you can use (8)………. energy, too.
A. effect
B. effective
C. effectively
D. effectiveness
Đáp án là B.