1 . 阅读下面短文，在空白处填入l个适当的单词或括号内单词的正确形式。

A new study suggests Jupiter’s icy moon (卫星) Europa produces much less oxygen than previously thought. The study was based on the data     1     (collect) by NASA’s Juno spacecraft.

The study involved Juno’s instruments measuring levels of oxygen     2     hydrogen molecules (分子) coming from Europa’s atmosphere. The data showed the icy moon produces about 1,000 tons of oxygen every 24 hours. NASA said that would be enough amount     3     (keep) a million humans breathing for a day.

However, the space agency noted those estimates of oxygen were much less than those measured in earlier studies about the moon. Europa is a little     4     (small) than the Earth’s moon. But it is still one of the largest moons in     5     (we) solar system. NASA observations have suggested     6     ocean exists beneath the thick layer of ice on Europa’s surface. Scientists estimate the moon’s ocean may contain a large amount of water,     7     is twice as the Earth’s oceans.

Since Europa was believed to have a large ocean under its surface,     8     (researcher) in the past identified it as a good candidate to hold the right conditions to support some form of life. That data came     9     (main) from telescope observations of oxygen levels existing in the moon’s icy surface. The new lower estimates of oxygen do not support the earlier observations. The team involved in the study said, in the future, more research     10     (need) to confirm the latest findings.

2 . Scientists say they have found detailed evidence of ancient rivers on Mars. The discovery supported existing evidence that Mars once had water. The researchers said their findings suggested rivers may have flowed on the surface of Mars for hundreds of thousands of years.

These images were captured by a camera on NASA’s Mars Reconnaissance Orbiter. The camera is able to take detailed pictures of the surface while orbiting the planet from about 400 kilometers away. A team of scientists studied the images, which showed a valley network on Mars.

The team was led by Francesco Salese, a geologist at Utrecht University in the Netherlands. Salese said the scientists studied sedimentary (沉淀物) rocks from a 200 meters high rocky cliff. Sedimentary rocks form when sedimented (使沉积) and transported by water or wind.

“These are sedimentary rocks and were formed by rivers that were likely active for over 100,000 years,” Salese said, adding even without the ability to examine the cliff area on Mars, the pictures show strong similarities to sedimentary rocks found on the earth.

William McMahon is another geologist who was part of the investigation team. He said sedimentary rocks have long been studied on the earth to learn what conditions were like on our planet millions or even billions of years ago. Another leader of the team was Joel Davis, a researcher with Britain’s Natural History Museum. He said scientists had never before been able to examine such a rock formation with such great detail. They created 3D images of the area to get a more detailed understanding of it, which suggested some ancient Martian rivers were several meters deep.

1. What is the text mainly about?

A．Scientists are able to study rock formation on Mars.

B．Scientists found evidence that there was water on Mars.

C．Mars sedimentary has many similarities to that on the earth.

D．A camera on NASA’s Mars Reconnaissance Orbiter took pictures of the planet.

2. How did researchers make the findings?

A．By comparing data.

B．By analyzing images.

C．By studying rivers on the earth.

D．By observing Mars through a telescope.

3. What was Joel Davis’ attitude towards the discovery?

A．Excited.

B．Unsatisfied.

C．Unexpected.

D．Disappointed.

4. Where is the text most likely from?

A．A novel.

B．A notebook.

C．A travel guide.

D．A newspaper.