1 . Imagine a warm spring day 66 million years ago. These could have been the very last moments of the dinosaur era when a city-sized asteroid struck Earth, killing off three quarters of all species on the planet. According to a study published in Nature on Feb 23,the asteroid hit in springtime.
Scientists have long been confused over the time of year the asteroid hit, and how some animals managed to survive while dinosaurs didn’t, according to USA Today.
Researchers in 20l9 discovered fossilized fishes in North Dakota that died shortly after the asteroid hit Earth. They examined the fossils with a particle accelerator and found out there was seasonal growth on the bone. All fish bone cell densities and volumes can indicate the season. Because the accelerator also could capture the sizes, researchers were able to determine when in the year the asteroid hit, Dennis Voeten told USA Today.
“I think spring puts a large group of the late Cretaceous biota in a very unprotected spot because they were out and about looking for food, tending to offspring after the winter,” Melanie During, the main author of the study.
In the Southern Hemisphere, it was autumn. Therefore, life in the Southern Hemisphere was a lot more prepared for this event.
It is unclear whether small animals in the Northern Hemisphere actually did worse than those in the south. There is evidence that Northern Hemisphere turtles were wiped out in the asteroid strike, after which their habitats were later repopulated by turtles from the south, Voeten told The Guardian.
Nothing much larger than a house cat survived the asteroid impact and many species would have been killed whenever it hit, Daniel Field, a professor at the University of Cambridge, told The Guardian.
1. Which probably helps find the time of year the asteroid hit?| A．The types of fossilized fishes. | B．The location of fossilized fishes. |
| C．The number of fish fossils in the area. | D．The volume and density of the fish bone cells. |
| A．The season of the hit. | B．The size of asteroid. |
| C．The group size of species. | D．The body shape of animals. |
| A．Chances of survival depended on it where the species lived at the time. |
| B．Many species could have survived the asteroid strike but for the season. |
| C．Many species had little chance to survive even if it was a different season. |
| D．Animals from the Southern Hemisphere were less affected by asteroid strikes. |
| A．The Science behind the Asteroid | B．Occurrence of the Natural Disaster |
| C．The Effect of Dinosaurs’ Extinction | D．New Research on the Asteroid Strike |
2 . When Did the First Stars Shine
Our universe is home to countless galaxies(银河), with each galaxy hosting hundreds of billions of stars. Each one is a ball of energies powered by the nuclear explosion of elements in their hearts.
Billions of years ago, there was a time before stars or before lights, called the Dark Ages. There used to be not enough material of high densities(密度)to cause nuclear explosion. Without nuclear explosion, there were no stars.
Those first stars burned fiercely and died quickly. None of them survived to the present day.
Recently, a team of astronomers used 70 hours of observing time to take pictures of six extremely distant galaxies.
Hopefully, upcoming missions, like NASA's James Webb Space Telescope, will be able to directly observe those galaxies in greater detail. And some star mysteries will be disclosed,
| A．Nevertheless, they left their mark. |
| B．Accordingly, there was no visible light either. |
| C．Each one also poured out light into the empty universe. |
| D．It was much darker than it is today with only a little light. |
| E．For example, when did the Cosmic Dawn exactly take place? |
| F．Based on their observations, they were able to estimate the age of the galaxies. |
| G．They're so far away that we can't capture them even with powerful telescopes. |
3 . Scientists have not found any signs of life on Mars yet,but they say a robotic vehicle called “Curiosity” is helping them learn a lot about the planet’s history and climate.
Curiosity landed on Mars in August 2012 after travelling through space for more than eight months.It was sent to Mars by scientists from NASA in the United States.
Curiosity is about the size of a car and has six wheels.It also has a robotic arm,cameras,and instruments that allow it to examine things it finds on the surface.Then it sends the information back to the earth.
Curiosity’s main task is to find out if anything could live on Mars,either now or in the past.On Nov.2,NASA scientists held a press conference (新闻发布会) to discuss what Curiosity had found in its first two months on Mars.
Curiosity has found soil that is similar to the sand formed by volcanoes (火山) on the earth.Scientists say that studying the minerals in Martian soil will help them understand what conditions were like on the planet in the past.Curiosity also found smooth stones like the ones found on river beds and seashores on the earth,where their rough edges have been worn down by water.Mars is very cold and dry now,but scientists say the smooth stones tell them that a river used to run through the place where they were found.
Curiosity has been testing the atmosphere around Mars for a type of gas called methane (甲烷),but so far it has not found any.On the earth,most methane is produced by plants or animals.Methane on Mars might indicate that some type of tiny plants or animals lived there.
Curiosity is the fourth robotic vehicle to be sent to Mars.It will continue to explore the planet for about two years.
1. Which of the following descriptions about Curiosity is TRUE?| A．It landed on Mars in January 2012. |
| B．It is small in size and has four arms. |
| C．It took over eight months to arrive in Mars. |
| D．It was sent to Mars by scientists from Russia. |
| A．there’s no air on Mars | B．Mars is warm and wet now |
| C．the soil on Mars is rich | D．there used to be water on Mars |
| A．smooth stones | B．rivers |
| C．robotic vehicles | D．volcanoes |
| A．some tiny animals once lived on Mars |
| B．there are no plants or animals on Mars now |
| C．the atmosphere around Mars is full of methane |
| D．Curiosity is designed to test the atmosphere around the earth |
| A．Humans benefit a lot by going to Mars. |
| B．Scientists will stop the research on Mars soon. |
| C．It is possible to build an earth-like environment on Mars. |
| D．A robotic vehicle helps scientists get useful information from Mars. |
