2025年8月23日上午场托福写作完整版答案及解析（含范文）

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　主题：独角鲸的tusk作用

　　First, the narwhal dwells and hunts within the Arctic Circle, where the sea is often covered with thick pack ice. Like other whales, the narwhal needs air to breathe and cannot stay underwater indefinitely. Eyewitnesses have reported seeing narwhals use their tusks to pierce through the ice sheet from below. The ability to break the ice in this way would give a narwhal access to air whenever it needed to take a breath. That would make it possible for narwhals to freely hunt in waters that are covered with ice.

　　First, if you apply pressure to a normal tusk. It will actually bend about thirty centimeters in any direction. This flexibility means that it cannot really be used for breaking through an ice sheet that is more than a few cent meters thick. The reason narwhals are able to spend long periods of time in the sea that's covered with ice is that the ice sheets typically break up by themselves in certain places. Supposed observations of narwhal ‘s piercing through an ice sheet, they have simply been narwhals seen sticking their heads out of the water in places where the ice sheet had already begun to break up.

　　Second, the tusk could serve as a weapon for fighting with other male narwhals as they compete for territory. Just as rams and male deer charge at one another with their horns or antlers. Male narwhals may charge or joust with another. Some observers have claimed to have seen aggressive clashing of tusks between male narwhals.

　　What the second theory in the reading passage probably refers to is a behavior observed in male narwhals called tusking. The reason that some observers may have mistaken tusking for an aggressive behavior is that they observed it from a distance. People who have observed the narwhals husking up close give very different accounts. Instead of tusking generally seem to gently rob their tusks. That's more consistent with some sort of communication role, rather than defending territory.

　　Third, the surface of the tusk contains many millions of microscopic holes connected to nerves. This configuration suggests that the tusk serves as a sensor that allows the narwhal to detect ocean properties, for example water pressure, temperature, salinity of the water, and even barometric pressure above the water's surface. The ability to sense such properties would be an important adaptation aiding in the narwhal's survival.

　　Third, as to the usefulness of the tusk for detecting properties of the ocean important for survival. Well, consider this. Almost all male narwhal have tusks, but very few female narwhal have the structure. Furthermore. Female narwhals live longer than male narwhals. If the function of the tusk was to give the animal information needed for survival, why wouldn't females have tusks as well? And since they don't. How do we explain their greater longevity?

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　主题：Anasazi 文明的迁移

　　Anasazi 文明的迁移是因为战争

　　1.好多重要地点甚至祭祀场所都被火烧了，就是是因为战争引起的火灾

　　焚烧祭祀地点是很多文明迁移前的传统，并不一定是敌人烧的

　　2.当地遗留了好多工艺品，说明原住民被消灭了而不是正常离开，因为正常离开是会带走那些物品的

　　如果是战争，获胜的一方应该会拿走工艺品，但现实是现场有很多遗留的工艺品，说明是原住民自己不要了:人们自愿离开受旱灾肆虐的地区时，往往会舍弃许多物品。他们只需带走力所能及的食物和饮水，其余非必需品则尽数遗弃

　　3.该文明正处于全盛时期，且资源充足，没有理由突然消亡

　　正是因为文明发达人口增长，所以他们更容易受缺水影响，最终选择迁移

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　主题：single-stream recycling的缺点和反驳

　　First, single-stream recycling can be dangerous for workers at the recycling center. While the sorting process for most recyclable materials is done by machine, glass needs to be separated and sorted by hand from other materials collected for recycling. Glass is often broken in the process of collecting the materials, so workers who sort glass from the other materials are at risk of being cut.

　　What about the potential for injury to workers who sort glass? Well, several steps can be taken to reduce the risk to acceptable levels. Workers can be given safety training and be monitored to make sure they follow the proper safety procedures. They are also required to wear protective clothing. There should be quick access to medical help if an injury occurs. These measures can ensure reasonable safety for workers.

　　Second, contamination—that is, materials not being separated well from one another—is practically unavoidable in single-stream recycling. The sorting process is complex and far from perfect; the different types of recyclables do not always get sorted correctly. For example, plastic can accidentally be shredded along with recycled paper. In cases when enough plastic gets mixed in with the paper, the overall recyclable material is considered contaminated and cannot be processed further. So instead of being used in new products, the material has to be discarded—just as though it had never been collected for recycling in the first place.

　　It's true that some of the collective material gets contaminated and so ends up as waste. But if you look at the overall picture. Single stream recycling actually reduces waste. Consider this. Placing all recyclables in a single container is easy and convenient, then that encourages many more families to participate in the recycling program instead of just throwing stuff away as waste. Which is what they did in the traditional system. So single stream recycling greatly increases the overall amount of material that gets recycled and reused. This more than makes up for the small amount that's contaminated.

　　Third, single-stream recycling systems are expensive to build. A single-stream system facility generally costs more than three times what a traditional recycling facility costs. Most cities and towns have limited funds, and if they already have a traditional system that works, there is no reason for them to spend the money to build a new, single-stream system.

　　Third, while single stream recycling systems are initially more expensive to build, they are less expensive to operate than traditional recycling programs. This is because you can reduce cost with single stream collection trucks. You see, in a traditional system, to pick up one families recycling required to trucks. One truck for one type of recyclable materials, another truck for the other types. The fuel and labor cost for operating the trucks were very high. With a new system, you can just use one truck to pick up all recyclables, which will save money. So once the initial cost of implementing a single stream recycling facility system are paid for the overall cost of operating, the program goes down dramatically.