2 . It’s unlikely that we’ll see a dodo, a flightless bird, walking this earth anytime again, according to Beth Shapiro, a evolutionary molecular biologist.

“When most people think about de-extinction, they’re imagining cloning,” Shapiro said. Cloning, the approach that created Dolly, the sheep in 1996 and Elizabeth Ann, the black-footed ferret in 2020, creates an identical genetic copy of an individual by putting DNA from a living adult cell into an egg cell from which the nucleus (细胞核) has been removed. Adult cells contain all the DNA needed to develop into a living animal. Egg cells then use that DNA as a blueprint to turn themselves into many kinds of cells——skin, organs, blood and bones——the animal needs.

“But no living cells from dodos exist. Instead,” Shapiro said, “you’d have to start with a closely related animal’s genome (基因组) and then change it into one similar to dodos.” For example， mammoths (猛犸) are also extinct，but they were very closely related to modern Asian elephants, so researchers are attempting to bring mammoths back from extinction by creating a hybrid mammoth with some mammoth genes replacing part of the elephant genome in an elephant egg cell. However, there are likely millions of genetic differences between the genome of an Asian elephant and that of a mammoth according to Shapiro.

As for the dodo, its closest living relative is the Nicobar pigeon. Mammoths and Asian elephants are pretty closely related, whereas it had been more than 20 million years since the dodo and the Nicobar pigeon had any common ancestors. Genetic differences between the two bird species are therefore much greater, making it a formidable task to create a successful hybrid in the lab, Shapiro said.

Even if scientists manage to bring dodos back, the island where they once lived is a very different place nowadays, which make it impossible to reintroduce dodos without major intervention.

5 . For children, space is magical — a whole world is out there, with so many things to learn and stories to read. Here are some children’s books about space and the solar system.

Mae among the Stars by Stasia Burrington

This beautifully illustrated picture book is attractive to young kids. It was inspired by the first African American woman in space, Mae Jemison. It tells the story of Mae as a little girl, who always knew she had big dreams about space. This is a great addition to a young kid’s collection, as a reminder to hold tight to dreams and never give up.

Space by Libby Jackson

This beautifully illustrated book gives kids a look at 50 women from around the world who were involved in exploring space in some way, from the 19th century to the present day. This is a perfect gift for young kids who want to know more about some of the lesser-known scientific achievements related to space exploration.

Chasing Space by Leland Melvin

This is Melvin’s story about being a football player-turned-astronaut, along with his recovery from an injury that nearly left him deaf. Kids will love reading his story about how he faced challenges and advanced ahead, and he also includes DIY experiments for kids to try, and a section of full-color photographs.

System and Beyond by David A. Aguilar

The book is full of beautiful illustrations of space, and is perfect for kids of all ages, exploring various planets and the solar system. Unlike other kids’ space book, this is a National Geographic book written and illustrated by an award-winning astronomer and space artist. Aguilar is also the former Director of Science Information and Public Outreach at the Harvard-Smithsonian Center for Astrophysics.

Plastic pollution at sea is reaching     1     (worry) levels. According to a review of hundreds of academic studies, it will continue to grow even if significant action is taken now     2     (stop) such waste from reaching the world’s oceans. The review by Germany’s Alfred Wegener Institute examined almost 2, 600 research     3     (paper) on the topic to provide an overview ahead of a United Nations meeting later this month.

As plastic breaks down into smaller pieces, it also enters the marine food chain,    4     (take) in by sea creatures from whales to turtles. What’s worse, some regions already contain dangerous levels of plastic, and others risk becoming     5     (increasing) polluted in the future. Getting that plastic out of the water again is nearly impossible,    6     policymakers should focus on preventing any more of it entering the oceans in     7     first place. Matthew MacLeod, a professor of environmental science at Stockholm University,    8     (involve) in a separate study not long ago,    9     also concluded effective measures are required immediately because of the possible global impacts.

While consumers can help reduce plastic pollution by changing their behavior, governments have to step up and accept     10     (responsible) for solving the problem. It’s a global problem and it needs global solutions.