综合写作：
Recently, interesting features called recurring slope streaks have been discovered on Mars. These are dark, narrow lines that appear on slopes in several Martian locations. The streaks seem to grow and shrink during the year, and they re – appear in almost the same places every year. This behavior suggests that they are formed by liquid water. If the recurring slope streaks truly mean there is liquid water on Mars, it would be a major new discovery. However, for the following reasons, some scientists do not believe that the streaks are formed by liquid water.
Sliding Rocks and Dust
The surface of Mars is often disturbed by objects falling from space. As these space objects collide with Mars, they disturb the Martian surface and cause loose pieces of rock and dust to slide down slopes. The sliding particles leave behind visible streaks that are similar to the recurring slope streaks. Some scientists have suggested that the recurring slope streaks might perhaps be caused by sliding rocks and dust, and not by water.
Cold Temperature
Another issue is that the surface of Mars may be too cold for liquid water to exist there. Water freezes at zero degrees Celsius, while the average temperature on Mars is minus 70 degrees Celsius. For that reason, the only water whose presence on Mars has been clearly established so far is frozen.
No Evidence from Specialized Instruments
One of our main sources of information about Mars is a research spacecraft that is currently orbiting Mars. The spacecraft carries specialized instruments that can detect various chemical elements and compounds on Mars’s surface. However, the instruments on board the spacecraft have so far failed to detect any liquid water in the recurring slope streaks.
学术写作：
Instructions: Your professor is teaching a class on sociology. Write a post responding to the professor’s question.
In your response you should:
- Express and support your opinion.
- Make a contribution to the discussion in your own words.
An effective response will contain at least 100 words.
Doctor Gupta
We have read studies that explain the negative impact of social media on both children and adults. Many believe that social media will remain widely used in the future, since it is both popular and useful in some contexts, but because of the problems it poses, it should be regulated in some way. In your opinion, should governments regulate social media platforms, or should social media companies regulate their platforms themselves? Why do you think so?
Andrew
I believe social media companies should regulate themselves. There are plenty of social media platforms on the market, so the competition is tough. For example, to appeal to parents, a social media platform could publicize that they have stringent regulations for children’s use of the platform, and in this way it could attract more users who care about children’s safety.
Claire
Social media companies should be taking an active role in combatting the negative effects, but that is not really happening. I hear many stories of false information spreading around, sometimes causing irreparable damage to people’s reputations. Therefore, the government should put stricter regulations on the companies, and they should be punished for not following the rules.
