In September 2020, a tragedy (悲剧) happened in Tasmania, Australia. As many as 380 pilot whales (座头鲸) became stranded (搁浅) in shallow water there and died. This might have been Australia’s largest stranding event on record, the BBC reported.

But mass (大规模的) whale stranding is not uncommon. For centuries, it has happened all over the world. Scientists say the cause is often unknown. But they have offered many different explanations.

Some say the whales chase fish for food and end up in shallow water because they are not paying attention to where they are going.

Others think the stranding has something to do with Earth’s geomagnetic field (地磁场). They say that a geomagnetic compass (罗盘) in whales’ brains helps them know their location. Changes in Earth’s magnetic field can affect the whales’ compasses and send them in the wrong direction.

Another explanation suggests that mass stranding is caused by the close relationships that whales have. Pilot whales travel in large groups. One lead whale might mistakenly lead the whole group to shallow water. “And if one gets into trouble, the others will not leave,” said Sheryl Gibney, a leading biologist from New Zealand. “Some will come in and try to help, they get trapped (受困) on the beach, then more will come.”

Unfortunately, once the whales become trapped, they will likely die. Less than 10 percent of stranded whales survive, according to the US National Oceanic and Atmospheric Administration.

China has a rich and colorful cultural history, and masks have played a major role in Chinese tradition in thousands of years. Why do people wear masks? The reasons are to protect their body, to hide themselves, or to do some amusement. In fact, masks are used all over the world.

African masks are usually made by a traditional style. There are many different kinds of African masks, but many of them represent animals. African masks are a part of full-body costumes and they are made for dancers. The dancers usually wear the masks in religious events.

Japanese masks have been used in many different performances such as dance, theater, festivals or religious events. They represent heroes, devils, ghosts, or some animals in the animals in the performances. Most of them are made of clay, cloth, wood or paper.

Greek masks are used to represent the spirits of nature during religious events. Also, theater actors use masks to show different characters. In Rome, devil and other masks are used in carnivals（节日）.