题干
Just like humans, birds rely on sound to communicate, too. Often, birds recognize their mates or young by sound rather than sight. Hungry young birds use begging calls to let their mothers know it is feeding time, and warning calls are other sounds given out frequently by the adults. In addition to all these regular calls, some male birds develop beautiful songs intended（打算）to attract the females.
A new study carried out by an American university shows that songbirds practice their songs even in their sleep. The research team discovered that the electrical brain activity of the birds that were asleep was similar to the brain activity produced when the birds were awake and singing. Clearly the bird stores a song after hearing it, then practices it later in its sleep. Scientists now believe the birds dream of songs to help them master the fine art of singing and that sleep plays a key role in the learning process！
It is commonly known that many songbirds learn to sing by listening to adult birds of the same species. If taught the song of an adult of another bird species, the chick grows up singing the new song and passes on the foreign song to its chicks. For instance, researchers carried out an experiment in which a male bullfinch（红腹灰雀）was raised by a female canary（金丝雀）. The bullfinch soon learned the canary's songs and when it was later mated to a female bullfinch, Mr. Bullfinch taught his children the canary's songs.
Early last year, a British survey of London's songbirds showed that the city's birds are losing their melodies. Birds could hardly hear one another over the traffic noise；as a result they had difficulty in learning songs and communicating with potential mates. And instead of copying the sweet notes of the adults, chicks were copying sounds, which they heard most often—namely car horns（喇叭）and mobile phones！
【小题1】What can we learn according to Paragraph 2？| A．Sleep helps songbirds master new songs. |
| B．Songbirds can even hear songs in their dreams. |
| C．The study was carried out by Australian scientists. |
| D．The brain activity of songbirds would stop in their sleep. |
| A．Because he wants to help them learn a foreign language. |
| B．Because he can't sing bulfinches' songs. |
| C．Because he wants to make them get along well with other birds. |
| D．Because the canary's songs are more attractive. |
| A．They have lost their voices. |
| B．They are losing their habitats. |
| C．They are bothered by the city's noises. |
| D．They tend to refuse to learn songs from adults. |
| A．The city's birds can learn more songs. |
| B．All birds learn foreign songs during their life. |
| C．It may be difficult for the city's birds to find their mates. |
| D．Young birds can tell the difference between songs and noises. |
答案(点此获取答案解析）
