Question

read the text.
wind energy
although the use of wind energy has flourished in the u.s. in recent years,
people all over the world have been harnessing the power of wind for
thousands of years. as early as 5000 bce, wind energy was used to propel
boats along the nile river. by 200 bce, simple wind-powered water pumps
were used in china, and windmills with woven-reed blades were grinding
grain in persia and the rest of the middle east.
new ways to use wind energy eventually spread around the world. by the
eleventh century, people in the middle east were using wind pumps and
windmills extensively for food production. merchants and returning crusaders
what is the main focus of the text?
the use of wind energy from ancient times to modern day
the important role of government in promoting the use of wind energy
the key reasons why wind energy is used more today than in the past

Explanation:

文本第一段提到风能的使用在近年来的美国蓬勃发展，且世界各地的人们数千年来一直在利用风能，还列举了公元前5000年、公元前200年等不同时期风能的使用情况；第二段讲述了风能使用的新方式传播到世界各地以及中东地区对风能的使用。整体围绕从古至今风能的使用展开。

Answer:

the use of wind energy from ancient times to modern day