Three million years may seem like a long time. But when you consider that planet Earth is more than 4.5 billion years old, it is a pretty short period of time.

The blue whale, 【小题1】 (weigh) more than even the biggest dinosaurs, is the largest animal that has ever lived. They can grow 【小题2】 30 meters long and be as heavy as 130,000 kilograms. 【小题3】 for millions of years, they were not nearly that large, scientists say. “All of a sudden — ‘boom’— we see them get very big, ” scientist Nick Pyenson said. He and other 【小题4】 (researcher) recently published an article on whale size. “It’s like going from whales 【小题5】 size of minivans (面包车) to longer than two school buses, ” Pyenson added.

The scientists believe that a change in the Earth’s climate caused whales 【小题6】 (get) so large only about 3 million years ago. This change led to food becoming more 【小题7】 (easy) available. An oncoming ice age made the ocean water cold and brought more nutrients, resulting in more food for large whales. Whales 【小题8】 were able to quickly eat a lot of food survived, and got 【小题9】 (large). Over the next three or four million years, the blue whales grew 10 times bigger than they 【小题10】 (be), the scientists say.

We have two apple trees in our backyard and our dog Prana loved apples. When she went outside, she would grab an apple, and stick it back in her mouth. The apples had been on the ground and were often 【小题1】 (mud), so I wasn’t always happy that Prana had brought them into the house. 【小题2】 (sense) my disapproval, she would turn her head so I wouldn’t see her 【小题3】 (hide) treasure. It was our little game. One autumn day, 【小题4】 (expect), we were hit by a big snow fall, for which no one was prepared. Prana went outside, digging holes and bringing the apples to the surface, so 【小题5】 could be seen above the snow. I wondered 【小题6】 she was doing this. When I called her 【小题7】 into the house, she had one apple in her mouth as usual. About five minutes later, I looked outside. Surprisingly, the yard was 【小题8】 (complete) covered with birds. It was before she entered the house that Prana 【小题9】 (dig) up all those apples for her bird and squirrel friends to eat. She knew that they wouldn’t have stored enough food to survive such 【小题10】 early winter!

In April 2017 , two giant pandas from China arrived at a zoo in the Netherlands. There, they 【小题1】( welcome) to the Chinese-style compound where they were to live. On May 30, after the preparations were complete, the day finally came【小题2】the pandas met their fans for the first time. People were excited because 【小题3】 zoo is the only place in the country where it is possible to see pandas. In fact, the last time there were pandas in the Netherlands was in 1987.