综合写作：
Although solar power technology has improved in recent decades, it has not yet overcome the problem of intermittency, the inconsistent availability of sunlight to produce electricity. While traditional methods of producing electricity can operate at any time, solar power is unable to produce electricity at night or in cloudy conditions when there is no visible sunlight. Scientists have proposed three solutions for capturing the extra energy from the sun during the daytime to use when there is little or no sunlight.
Batteries
First, the simplest solution to solar power intermittency is to use batteries, which store energy during the day until it is needed to produce electricity at night or in cloudy weather. In the past, solar battery storage has not been an economical option because the batteries were very expensive, but new technologies for manufacturing batteries have helped make them more affordable.
Thermal Storage
Another solution to solar intermittency is called thermal storage. This can refer to a few slightly different processes that typically involve storing energy as heat rather than as electricity, as batteries do. When there is no visible sunlight, energy from stored heat can be used to spin a
giant fan called a turbine, which can then be attached to a generator that will produce electricity.
International Grids
Finally, many experts believe that solar intermittency is only a problem of scale. Larger, more flexible power grids (networks for conducting electricity) could extend across international borders to solve the problem. For example, one proposed power grid would take advantage of varying climates across continents. When it is summer in the southern hemisphere and it is winter in the northern hemisphere, the extra sunlight in the southern hemisphere could be used to provide electricity to the northern hemisphere.
学术写作：
Your professor is teaching a class on business management. Write a post responding to the professor’s question.
In your response, you should do the following.
- Express and support your opinion.
- Make a contribution to the discussion in your own words.
An effective response will contain at least 100 words.
Dr. Achebe
In the next few weeks, we’ll be talking about urban traffic management. Let’s begin by discussing one popular idea – creating car-free central zones. Some cities around the world have recently designated their downtown areas as automobile – free, which means that vehicles are not allowed to enter the city centers. Do you think that more cities should make their central zones car – free? Why or why not?
Claire:
I support the idea of creating car – free central zones because it would bring an important benefit to city residents – it would promote their health. The government would encourage people to walk or bike more instead of driving everywhere. It would be a great way to incorporate exercise into people’s daily lives.
Paul:
That sounds like a good idea, but I have my doubts about it. My main concern is that many businesses located in the city center, such as shops and restaurants, may be affected because customers will no longer be able to drive directly to these establishments. For some customers, if they can’t drive, they simply won’t go.
