综合写作：
Velvet trees are fast-growing plants that can grow up to fifteen meters tall. They are native to South and Central America and were first imported to Hawaii for decorative purposes in the mid-twentieth century. Velvet trees are damaging Hawaiian ecosystems by blocking the sunlight needed by native plants. Also, a single velvet tree produces large numbers of seeds every year, so the trees reproduce and spread more rapidly than native plants. Scientists are examining strategies for controlling velvet trees in Hawaii.
One method is to physically remove velvet trees. The leaves of the velvet tree have a distinctive coloration and can grow up to 1 meter long, which makes velvet trees easy to identify. Once identified, younger trees can easily be pulled out of the ground by hand. Older, larger trees that are too difficult to remove by hand have to be cut down.
A second strategy is using the velvet tree’s naturally occurring enemies against it. By investigating the tree’s native habitat (environment), scientists have identified one such enemy—an infectious fungus. The fungus works by creating a leaf infection that gradually causes velvet trees to lose their leaves. Significantly, the fungus does not harm any of Hawaii’s native plants, infecting only the velvet tree. The introduction of the fungus to Hawaii is expected to drastically decrease the spread of velvet trees.
A third approach is to eliminate the human dispersal of velvet-tree seeds. Several times a year, velvet trees produce thousands of seeds, most of which fall to the ground around the trees. When people enter areas with velvet trees, these tiny seeds get on their shoes, clothes, and equipment. By such means, the seeds are carried to new areas, where they can take root. By thoroughly cleaning their clothing and equipment, people can help prevent velvet trees from spreading.
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.
