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阅读短文，回答问题 European researchers say they have created a process that can produce oxygen from moon dust. The process could provide a major source of oxygen for humans taking part in moon exploration activities in the future. Researchers from the European Space Agency, or ESA, carried out the experiments at a laboratory in the Netherlands. The team says ESA's experimental "plant" was able to successfully produce oxygen from simulated moon dust. The dust is part of a material known as regolith, a top layer of dirt and rock pieces that sit on the surface of the moon. Samples of regolith returned from the moon have confirmed that the material contains about 45 percent oxygen by weight. However, the oxygen is chemically locked in the form of minerals or glass, so it is not easily available for use. Having real samples of regolith from the moon made it possible for the researchers to create the simulated moon dust material used during testing. The oxygen extraction(提取)process is carried out using a method called molten salt electrolysis(熔盐电解). This includes first placing the regolith in a metal container. Calcium chloride salt is added to the mixture, which is then heated to 950 degrees Celsius. At this temperature, the regolith remains solid. Next, an electrical current is passed through the material. The researchers say it is this step that results in oxygen being extracted from the regolith. The study reported that up to 96 percent of oxygen in the simulated moon dust was extracted during the experiments. ESA's long-term goal is to design an oxygen-producing "pilot plant" to operate full-time on the moon. The first technology demonstration of the system is expected to take place in the middle 2020s. Beth Lomax, a lead researcher on the project, said, "Being able to acquire oxygen from resources found on the moon would obviously be hugely useful for future lunar settlers, both for breathing and the local production of rocket fuel. "The researchers reported that" as a bonus, "the process also results in the production of usable metallic materials. ESA and the US space agency NASA are both working on plans to return human beings to the moon. NASA has set a goal for 2024 with the aim to keep humans on the moon for long periods. （1） Why is oxygen from moon dust difficult to use? A . It is tough for human beings to get moon dust. B . It is chemically fixed in materials or glass. C . The conditions of moon dust are terrible. D . There exits only a little of it. （2） What is the main idea of the third paragraph? A . What molten salt electrolysis is. B . Where the value of the study lies. C . How oxygen is extracted from moon dust. D . What is necessary in the oxygen extraction process. （3） What is Beth Lomax's attitude towards the possibility of getting oxygen from moon dust? A . Positive. B . Skeptical. C . Cautious. D . Indifferent. （4） What can be the best title for the text? A . Recent Studies of Moon Dust by Researchers B . How Researchers Extracted Oxygen from Moon Dust C . Potential Significance of Oxygen Extracted from Moon Dust D . Researchers Report Extracting Oxygen from Moon Dust Successfully 答案： B C A D

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