It takes two to duet  , and one question for scientists is how these coordinated   performances arise -- in birds. Are they the result of cooperation, a way in which one pair signals to others that they've got it together? Or are they the result of conflict, evolving to avoid one partner's song interfering with the other's? A study of duetting in Peruvian warbling antbirds  suggests that it might be a little of both, and that context is everything. Joseph A. Tobias and Nathalie Seddon of the University of Oxford show in Current Biology that sexual conflict can cause the female of a pair that normally cooperates to "jam" the male's song by singing over it. The researchers exposed antbird pairs to recorded songs of other antbirds and monitored the songs the pairs produced. In one experiment, they played the songs of an intruding pair. In this case, the resident pair "both are likely to lose their territory, so both should cooperate," Dr. Tobias said. And they do. They produce a coordinated duet that in effect tells the intruders to keep away. But when the researchers played the song of a single female, the pair behaved differently. "You'd expect the resident female to be highly motivated to defend her position in the partnership," Dr. Tobias said. And that's what occurs. The male sings its heart out, flirting  with the single female, and the female of the pair does its best to interfere with the song by singing over it, apparently to make her mate less attractive to the other female. "It's clear that the male doesn't like what she's doing," Dr. Tobias said. The behavior "breaks up what is otherwise a very cooperative situation into a more complicated signal," he added. It's the first evidence of this kind of signal jamming among pairs, Dr. Tobias said. And in that it leads the male to alter its song to avoid the female's interfering notes, it shows that this kind of conflict could, over a long period, drive the evolution of coordinated song. What is the key factor of antbirds' duet? A) Their cooperation. B) Their conflict. C) The context. D) Their instinct.
C
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What will you be doing when you are 26 years old? Studying at university or working for a living? Take a look at what Albert Einstein was doing at the age of 26. 100 years ago, Einstein was working in Switzerland. His hobby was physics. Without much money or help, he wrote five papers  for a physics magazine. Three of these greatly changed the study of physics and our understanding of space, time, light and matter . His most famous work is on the Theory of Relativity . Einstein was given the Nobel Prize for his discoveries. Although he also did many other things later, the years 1905 has been called Einstein's "Year of Wonders". It has been 100 years since then. Because of this, the UN has named 05 the World Year of Physics. Today, over fifty years after Einstein's death, a question is asked,  " Will there ever be another Einstein?" It may take a long time. After all, Einstein was born more than 200 years after Sir Isaac Newton, another great scientist. Besides, physics is a different field now, and education is different, too. Even if you can't be the next great scientist, it is still helpful to remember some of the things that made Einstein great. He thought independently  and read widely. He left with us a formula  for life: If A is a success in life, then A="X+Y+Z." X is work, Y is play, and Z is keeping your mouth shut. The UN has named 05 the World Year of Physics because    _    . A) Einstein is 100 years old this year B) Einstein has been dead for more than 50 years C) there have been other great discoveries after Einstein's death D) it is the 100
D
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Jane arrives at Thornfield, having been met at the George Inn. Mrs. Fairfax confuses her a little at first, because _ is so informal and welcoming. But in due course Jane discovers that Mrs. Fairfax is the housekeeper. Jane's pupil, Adele Varens, is the eight-year-old French child under the legal protection of Mr. Edward Rochester, the owner of the house. (We learn later that her mother had claimed she was his illegitimate daughter. Mr. Rochester is not convinced by this claim, but felt he could not leave the little girl poor when her mother died.) Adele is a pleasant little girl, even if she is not a particularly eager student. Life goes on very peacefully for three months, until the return of Mr. Rochester. Jane first meets him on his horse, and her description of him is quite fanciful. He takes a fall and Jane helps him, although she does not know who he is until they are both back at Thornfield. It is obvious to the reader, although not to Jane, that the reason why Mr. Rochester stays at Thornfield much longer than usual is that he finds her company enjoyable. Jane, unknowingly at first, falls in love with him. Their closeness is very apparent. There is something about Thornfield that is mysterious. Jane is encouraged to focus her attention on the servant Grace Poole, who is Mr. Rochester's mad wife Bertha Mason's keeper at Thornfield, and whose drunken carelessness frequently allows Bertha to escape and do something violent. It is clear to the reader, though, that Mr. Rochester's emotional engagement is immense. When his bed is set on fire, Jane rescues him, but does not understand why the matter is not pursued, despite Mr. Rochester assuring her the criminal is Grace. The next morning Grace behaves as though she has done nothing wrong. Eventually, Mr. Rochester leaves, to go to a house party. He brings everyone at the party back with him, transforming the atmosphere in the house, and delighting Adele. One of the guests is Blanche Ingram, whom Mr. Rochester is confidently expected to marry. However, it... Why is Mrs. Reed bitter towards Jane? A) Because Jane inherited Mr. Reed's fortune. B) Because Jane didn't get along well with her cousins. C) Because Jane's mother was more beautiful than Mrs. Reed. D) Because Mr. Reed loved Jane more than his own children.

D
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