50. What is the best title of this article？

　　A. Pills help forget terrible memories

　　B. Pills help forget the past

　　C. How to forget the past D. How terrible memories do harm to us

E
　　It’s great to go on vacation, but it’s also nice to come home. Migrating (迁徙) birds seem to feel the same way. Birds such as black-tailed godwits (黑尾塍鹬), a migrating bird that can be found in Europe, Asia, north Africa and north Australia, fly south every winter. Then, they return home to spend the summer months with their life long partner.

　　Now, scientists have found, pairs of godwits often return to their summer breeding (繁殖) grounds within three days of each other, even though they spend the entire winter apart. It’s as if they arranged the date that they would meet up again.

　　Researchers in England, put coloured leg bands on the birds. Then, they asked birdwatchers around Europe to report by email when and where they saw the birds during the winter.

　　The simplest way for birds to return at the same time would be to spend the winter together. After all, if they’re in different places, they can’t call each other on the phone and talk about when they’ll meet again.

　　But, the survey found that couples usually spent their winters in different countries up to 1,000 kilometres apart. One male, for example, spent the winter on the coast of Ireland while his mate was in France.

　　These findings are important for protecting the birds, scientists say. Black-tailed godwits live for up to 25 years. They spend their summers in Iceland, where they mate, but they spread all over other parts of Europe in winter. Once a pair mates, there’s a 90 per cent chance that they’ll return to mate with each other again the next year. So, protection of their wide web of holiday destinations (目的地) is very important.

　　How do the birds arrange their date of return? Unless scientists find their feathered cellphones, that question will remain a mystery.