We usually see baby ducks paddle in     1     straight line behind their mother in a pond. That ducks swim in a row is such a common phenomenon that it’s become an idiomatic expression. Many studies have looked at why ducklings do this.

    2     turns out that the baby ducks ride on their mom’s waves to save energy. For a long time, scientists didn’t understand why swimming in this pattern helps baby ducks save energy. A team of scientists in Scotland and China set out     3     (find) the answer. Its findings     4     (publish) earlier this year reveals ducklings save energy by staying in line behind their mother, where they can ride the waves created in her wake.

Zhiming Yuan, a naval architect, worked on the study. He made a     5     (create) computer simulation of duck waves and studied the simulation. He found when a duckling swims     6     its own, it kicks up waves causing wave drag, which makes it much     7     (hard) for the duckling swimming. However, to our     8     (amaze), when ducklings swim in their mother’s wake, the wake drag is reversed. The baby duck feels a push instead of a drag. And when ducklings line up     9     (neat) behind their mom, they share with each other. Each duckling in the line     10    (pass) its waves along to the ones behind it. So, ducks swim in a row.

A study     1    (lead) by Stanford University explores the influence microplastics(塑料微粒) have on whales. Microplastics are pieces of plastic less than five millimeters in length and are now frequently found     2     the whales live. The team found the whales mainly find food from 50 to 250 meters below the surface. At such depth, the highest concentrations of microplastic in the open ocean take place. Researchers estimate that up to 10 million pieces     3    (consume) by each whale per day.