Each year, we take more than 100 billion tons of natural materials from the earth     1    (make) the products we buy. However, about two-thirds of them     2     (eventual) becomes waste, including almost 3 billion plastic bottles     3     end up in the ocean every year.

Since the 1860s, we     4     (follow) a common business model. Industries take natural materials, they make things, we use them, and then we throw them away. Environmentalists and economists warn that this model is not good for the environment, so they suggest     5    new choice: a circular economy (循环经济).

A circular economy     6     (base) on the idea of reducing waste by keeping the natural, materials and products in use for much     7     (long). It works in a circle, very much the way nature does. The circular economy uses a range of     8     (strategy), such as recycling and reusing. In a circular economy, products are designed to be long-lasting and easy to repair from the     9     (begin). In this way, we can keep the balance     10     human and nature.

Antarctica is one of the hardest-to-reach places on Earth. But a recent report shows ships     1    (sail) to Antarctica have connections to ports around the world. That greatly raises the chance that plants or animals     2    the outside could invade (入侵) this protected area.

Invasive species are animals or plants that arrive in a place where they don’t normally live. When invasive species     3    (bring) to a new place, they can often spread quite quickly, which can force out other plants and animals that live there     4    (natural).

In other parts of the world, invasive sea animals and plants have caused trouble after     5    (they) arrival. They often came     6    (attach) to the outside of ships. The conditions in Antarctica are tough, and many animals could never live there. But scientists worry whether the species     7    live at the North Pole and are already used to extremely cold conditions could survive in Antarctica. As the oceans warm, even     8    (many) kinds of plants and animals may be able to survive there.

The report makes several     9    (suggestion) for improving the situation. One idea is for ships to be coated in a special covering that makes it hard for invasive species to stick to them. Ships without this kind of coating could be cleaned regularly. Moreover, countries could require ships to have an     10    (inspect) or some other proof that they aren’t carrying invasive species before they leave the port.