1 . Killer whales, or orcas, are known for their severe attacks on sea animals but they have never posed a threat to humans. However, since late July, the normally social animals have been intentionally attacking sailboats off the coasts of Spain and Portugal.

The strange behavior first surfaced on July 29, 2020, when a 46-foot boat was repeatedly attacked for almost an hour by nine orcas, causing the boat to rotate(旋转) 180 degrees and having its engine switched off. Since then, over 30 more similar incidents have been reported. On September 23, 2020, Spain's government banned boats of less than 50 feet in length from sailing in the 60-mile stretch of the Atlantic coastline between Ferrol and the Estaca de Bares Cape, where the attacks have been occurring.

Researchers across the world are trying to explain the orcas' behavior. Some believe it could be a result of the overfishing of the bluefish tuna - the orcas' primary food source -which has left the area's killer whales starving and unable to feed their babies. "I saw them look at boats carrying fish. I think they know humans are somehow related to food shortages, "says Ken Balcomb, senior scientist at the Center for Whale Research in Washington, USA. The environmentalists believe the sudden increase in boat traffic and fishing activities, after months of absence due to restrictions on human activity last spring, could also be contributing to the agitation.

However, Alfredo López, a biology professor in Galicia, Spain, thinks the attacks are defensive measures the orcas adopted to protect themselves against boat injuries. The researcher came to this conclusion after looking at the of the videos of a few incidents and noticing that two of the young killer whales involved had serious injuries. Hopefully, the experts will be able to find a way to restore the harmony between the animals and the humans soon.

1. What do we know about orcas in paragraph 1?

A．They are friendly to humans.	B．They have changed their behavior.
C．They are famous for hunting skills	D．They have met tough living conditions.

2. Who hold(s) the idea that fishing activities caused the incidents?

A．Ken Balcomb.	B．The environmentalists.
C．Alfredo López.	D．Spain's government.

3. What does the underlined word "the agitation" in Paragraph 3 refer to?

A．The attacks.

B．Food shortages.

C．The overfishing.

D．Human activities.

4. What might be a suitable title for this text?

A．How do killer whales attack humans?

B．Why Are Killer Whales attacking Boats?

C．How can we live in harmony with animals?

D．Why are boats banned from sailing on the sea?