Do you know about Psephurus gladius? It's a Chinese paddlefish known as "king of all national freshwater fish". However, it is announced that the Chinese paddlefish living in the Yangtze River has become extinct（灭绝的）.

A paper from Science of the Total Environment shows that the largest freshwater fish in China might have gone extinct between 2005 and 2010.Wei Qiwei, author of the paper, said in September, 2019, some experts supposed that the first-class protected fish had been extinct already.

The Chinese paddlefish was about 2 to 3 meters long and could grow longer than 7 meters. The fish had lived on the earth for 15 million years. The latest discovery of the fish was made in 2003.Scientists helped the fish to return and tried to track（追踪）it. Unluckily, a boat accident caused the tracking efforts to fail. Since then, no discovery has been reported and no such fish has been kept in captivity(圈养).

"The Chinese paddlefish was so big that it was hard to raise in captivity," Wei said. Between 1984 and 1993, he once tried to save four fish, but only one stayed alive and returned to the river.

The extinction of the fish has called public attention as people expressed sadness over the death, hoping such animals would be better protected so that future generations could see them. From Jan 1,2020, China began a 10-year fishing ban（禁令）on important areas of the Yangtze River to protect Biodiversity（生态多样性）in China's longest river.

【1】It can be learned from the passage that ____________.

A.the Chinese paddlefish was hunted too much in the past

B.the Chinese paddlefish was the largest freshwater fish in the world

C.the Chinese paddlefish could grow to be over 7 meters in length

D.the Chinese paddlefish has never been seen so far

【2】What happened after the boat accident mentioned in Paragraph 3?

A.Some scientists saved the fish. B.People failed to track the fish.

C.The fish lost its life. D.The fish was kept in captivity.

【3】Why couldn't the Chinese paddlefish be raised in captivity?

A.Because of its living habits. B.Because of its large size.

C.Because of is special diet. D.Because of the high cost.

【4】What's the writer's purpose in writing the passage?

A.To show people's sadness about the fish's death. B.To explain how the fish died out.

C.To call on people to protect animals. D.To introduce a first-class protected fish.