The question is often asked whether every butterfly makes the round-trip journey every year . And the answer is no . The average monarch lives about nine months . So one flying north might lay eggs in Louisiana and then die . The eggs of that generation may be found in Kentucky ; the eggs of the next generation may end up in Wisconsin or Michigan . The last generation of the season , about the fourth , will make their way back to Mexico and restart the journey .
Scientists learn about monarchs’ migration by catching and making marks on the insects . By
recatching a monarch with such a mark and noticing where it came from , the next scientist can get to know things like the butterfly’s age and its routing（路线）.
56. One of the places where monarchs spend the winter is .
A. the Gulf of Mexico B. an area in Mississippi
C. a forest in Mexico D. a plain in Texas
57. The routing of monarchs’ migration can be learned .
A. by examining the marks made on them
B. by collecting their eggs in the mountains
C. by comparing their different ages
D. by counting the dead ones in the forests
58. What is the subject discussed in the passage ?
A. Migration of monarchs . B. Scientists’ interest in monarchs .
C. Winter home of monarchs . D. Life and death of monarchs .

B
SYDNEY: As they sat sharing sweets beside a swimming pool in 1999 , Shane Gould and Jessicah Schipper were simply getting along well , chatting about sport , life and “ anything else that came up . ”
Yet in Sydney next month , they will meet again by the pool , and for a short time the friends will race against each other in the 50-meter butterfly（蝶泳）in the Australian championships at Homebush Bay .
Gould , now a 47-year-old mother of four , has announced she will be making a return to elite competition（顶级赛事）to swim the one event , having set a qualifying（合格的）time of 30.32 seconds in winning gold at last year’s United States Masters championships . Her comeback comes 32 years after she won three golds at the Munich Olympics .
Schipper , now a 17-year-old from Brisbane with a bright future of going to Athens for her first Olympics , yesterday recalled（回忆）her time with Gould fie years ago .
“ I was at a national youth came on the Gold Coast and Shane had come along to talk to us and watch us train , ” Schipper explained . “ It seemed as if we had long been god friends . I don’t know why . We just started talking and it went from there . ”
“ She had a lot to share with all of us at that camp . She told us stories about what it was like at big meets like the Olympics and what it’s like to be on an Australian team . It was really interesting . ”
Next time , things will be more serious . “ I will still be swimming in the 50m butterfly at the nationals , so there is a chance that I could actually be competing against Shane Gould , ” said Schipper , who burst onto the scene at last year’s national championships with second places in the 100m and 200m butterfly .
59. What is the passage mainly about ?