题目内容：

The Arizona desert is really dry. Anyone stuck in it without water would die from dehydration（脱水）within three days. Unless, that is, they had one of Omar Yaghi’s next-generation water harvesters. Although daytime humidity（湿度）is only about 10 per cent, this rises to 40 per cent at night, which means there’s enough water in the atmosphere to support life — if it can be changed into liquid form.

That’s exactly what Yaghi’s device does. It’s a box about the size of a small microwave oven designed to suck the humidity from the air at night and turn it into drinking water the next day using only the heat of the sun as its power source. What makes it work is a powder called a metal-organic framework (MOF), which at normal temperatures attracts water molecules (分子) onto its surface. Warm it up and the water is released, each harvest producing one-third of a cup of pure drinking water. “With further improvements, a device, the size of a washing machine, could produce enough water for the basic needs of a household,” says Yaghi, a chemist at the University of California.

One-third of the world’s population lacks safe drinking water; for them such a device could be a lifesaver. But that’s not the limit of the MOF technology.

Just as MOFs can help solve the problem of water shortage, they offer a way of reducing a lot of greenhouse gases. In April this year, the carbon dioxide levels in the atmosphere hit an 800,000-year high, contributing to climate change. Recent research suggests ways that MOFs might be able to help mitigate（缓解）this danger to the Earth’s ecosystem.

An international team led by chemists from the University of Manchester, UK, reported in 2018 that they had developed an aluminum (Al)-based MOF that can selectively and repeatedly remove another gaseous pollutant, nitrogen dioxide (NO2), from the surrounding atmosphere. This discovery could lead to air-related technologies that seize and change large quantities of other gases, such as carbon dioxide, to reduce air pollution.

In 2017, a MOF startup pioneer NuMat Technologies employed MOFs to safely store and deliver dangerous gases. For a given pressure, a tank containing a MOF holds more gas than one without. Or, to put it another way, if a gas tank has a MOF in it, then it does not need to be as highly pressurized in order to hold the same amount of gas, making it safer and less likely to explode, and possible less expensive.

Now, about two dozen companies in the past five years are known to be pursuing MOFs, from small startups to larger chemical and automobile companies. And QYResearch forecasts that the MOF market will grow from $70 million in 2017 to $750 million in 2025. “The potential here is just endless,” says Yaghi. “As cheaper materials come into focus, there will continue to be even more opportunities for commercialization.”

1.MOF changes the sucked humidity into water by ________.

A. lowering the temperature

B. collecting carbon dioxide

C. recycling dangerous gases

D. absorbing the heat of the sun

2.Aluminum-based MOF can be used to _______.

A. reduce greenhouse gases

B. produce household water

C. deliver dangerous gases

D. release water molecules

3.It can be learned that under the same pressure, a tank with a MOF will _______.

A. cost more money    B. cause more explosions

C. hold more gases    D. afford more crashes

4.The main purpose of this passage is to ______.

A. explain how to use MOF

B. describe the future of MOF

C. persuade people to buy MOF

D. introduce the functions of MOF