Why don't birds get lost on their long flights from one place to another?

Not long ago, experiments showed that birds rely 【小题1】 the sun to guide them during daylight hours. But what about birds 【小题2】 fly by night? Tests with artificial stars have proved that certain night-flying birds are able to follow the stars in their long distance flights.

A dove had spent its lifetime in a cage and had never flown under a 【小题3】 (nature) sky. Yet it showed an inborn ability 【小题4】 (use) the stars for guidance. The bird’s cage 【小题5】 (place) under an artificial star-filled sky. The bird tried to fly in the same direction as that 【小题6】 (take) by his outdoor cousins. Any change in the position of the make -believe stars caused 【小题7】 change in the direction of his flight.

Scientists think that doves, when 【小题8】 (fly) in daylight, use the sun for guidance. But the stars are obviously their main means of 【小题9】 (fly). What do they do if the stars are hidden by clouds?  Apparently, they find their way by such landmarks as mountain ranges, coastlines, and river courses. But when it’s too dark to see these, the doves circle 【小题10】 (help), unable to get their position.

Giant panda Fu Bao arrived at Chengdu Shuangliu International Airport in Sichuan province on Wednesday, returning from South Korea.

According to the agreement on giant panda 【小题1】(protect) and research cooperation, overseas-born giant panda cubs are to return to China between the ages of 2 【小题2】 4. Fu Bao’s return【小题3】(schedule) for this year. According to Everland Park, over 1,000 visitors came daily to bid farewell to her before the scheduled departure.

【小题4】(accompany) by veterinarians and caregivers from the China Conservation and Research Center for the Giant Panda and Everland Park of South Korea, Fu Bao headed to the isolation and quarantine area.

In   【小题5】(prepare) for Fu Bao’s return, the giant panda center has set up a quarantine facility at the Wolong Shenshuping Base. During the isolation and quarantine period, 【小题6】team of experts will help it adapt to its new living environment.

Fu Bao’s parents reached the park in March 2016 from the giant panda center in China, 【小题7】 (mark) the beginning of collaborative research between the two countries. After giving birth 【小题8】 Fu Bao in 2020, they bred another pair of female twin cubs in July last year.

According to the giant panda center, China and South Korea 【小题9】(cooperate) in the fields of giant panda conservation and breeding, disease prevention and control, and public education over the past eight years, 【小题10】(effective) promoting the conservation of endangered and vulnerable species in both countries.

Two pandas, Da Mao and Er Shun, sent to Calgary Zoo in Canada in 2014, are being sent back to China two years ahead of schedule. The animals feed on fresh bamboo, 【小题1】 is especially flown in for them from China. Some joked that the pandas are "leading too luxurious life". But with the pandemic（流行病）【小题2】（disturb）flights, fresh supplies have got 【小题3】（delay）. According to the zoo staff, pandas are picky eaters and will reject bamboo that has spent a lot of time in transport.

The pandas are 【小题4】（possible）just two out of hundreds of animals who might be suffering because of the pandemic. In April, CNN reported that financial issues were forcing a zoo in Germany 【小题5】（kill）some animals to feed the others and similar things 【小题6】（report）from the United Kingdom and other countries too.

Our focus is on human welfare（人类幸福）all the time，【小题7】 animal welfare should not take 【小题8】 back seat. So, we should say they are fortunate enough to have a hometown to return 【小题9】 when faced with difficulties. Because China has successfully controlled the outbreak, it can consider getting the pandas back and providing fresh bamboos for them. In fact, resumption（重启）of flights, reopening of zoos and returning home can be 【小题10】（benefit ）to millions of animals. It is hoped that in some other countries the epidemic can get controlled soon so that all animals can benefit.