理工类考试辅导：补全对话Listening to Birdsong
A male zebra finch1 chirps away2to himself. Suddenly he notices a female bird nearby. He realizes he has an audience and immediately changes his song. Can the female tell the difference in his performance? According to a new study， the female zebra finch knows. And she prefers the special trills he creates when he sings to her. A male zebra finch changes his song when singing to a female in ways that people can barely detect. But ~the female finch can tell the difference.
Scientists had noticed slight variations in the songs of mal~ zebra fmches based on whether they were singing alone or whether there was a female (and potential mate) nearby. With an audience， the males sped up the pace of their songs and controlled the notes they used.
For this study， researchers Sarah C. Woolley and Allison Doupe at the University of California， San Francisco decided to focus attention on the listening females， which have not been well studied in the past.
In the study， Woolley and Doupe set up ，a long cage with a sound speaker at each end. One broadcast the sound of a male zebra finch singing to himself， like someone singing in the shower. The other speaker broadcast a male performing for a female audience， as if he was giving a concert.
Female birds were placed between the two speakers. Some of the birds had mates， others didnt. The females shifted around a bit， and then most of them hopped over to sit beside just one speaker. All the birds that made a clear choice liked songs meant for a female audience， even if theyd never met the male.
Mated females also had a chance to listen to two different performance songs， one from an unknown male， and one from their mate. They spent more time listening to the concert version of their mates songs. This suggests that after a while， females learn to recognize--and prefer—the songs of their mates.
Scientists then studied the brains of the females. They found certain areas of the brain perked up3 when the birds listened to the concert songs. These brain areas may be involved in recognizing and evaluating the songs， and storing the memories of them.
This research deals with whats called directed communication， when the communicator， or sender， focuses the message for a specific audience. One example is the way moms speak to their babies. Mothers around the world use the same sort of highpitched4 sing-song chatter， and the babies respond best to those sounds. Songbirds are one of the only other species known to learn their communication， in this case their songs.
词汇：
finch n. 雀科鸣鸟 perk v. 使振作，使活跃
chirp v. (鸟)鸣 morn n. 妈妈(等于英国英语mum)
trill n. (鸟的)啭音；颤音 chatter v. &n喋喋不休，唠叨
注释：
1. zebra finch： 斑胸草雀
2. chirp away： 吱喳而鸣。away有continuously和steadily的意思。
3. perk up ： 活跃起来，振作精神
4. high-pitched： 活跃起来，振作精神
练习：
1. What does the first paragraph say about zebra finches?
A)Male zebra finches like to sing to female zebra finches.
B)Male zebra finches sing louder than female zebra finches.
C)Male zebra finches change their songs in female zebra finches presence.
D)Male zebra finches like to listen to female zebra finches sing.
2. What did the researchers fred in their study of female zebra finches?
A)Female finches liked songs male finches sang for them.
B)Female finches only liked songs male finches sang for their mates.
C)Female finches liked to listen to songs from both speakers.
D)Female finches chose the best male singers as their mates.