Question

阅读下列短文，从每题所给的四个选项（A、B、C和D）中，选出最佳选项。 　　Monarch butterflies（黑脉金斑蝶）are a common summer sight in the northern United States and Canada．These large orange and black insects（昆虫）brighten parks and gardens asthey fly lightly among the flowers．What makes monarchs particularly interesting is that they migrate（迁飞） — all the way to California or Mexico and back．They are thought to be the only insect that does this． 　　Every year in the late summer monarchs begin their journey to the south．Those heading for Mexico go first for the Louisiana-Mississippi area,then fly across the Gulf of Mexico into Texas．Once in Mexico,they settle themselves in one of about fifteen places in a mountain forest filled with fir trees．Each place provides a winter home for millions of monarchs．The butterflies are so many that they often cover entire trees．When spring comes,they begin their long journey north． 　　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）． (1) 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 (2) 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 (3) 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．

Answer 1

答案：1．C;2．A;3．A;
解析：

(1)	解析：全文提到，黑脉金斑蝶是特殊的蝴蝶，它们像侯鸟一样迁徙，有的迁至California （本文没有详述）有的迁至Mexico，并在那里的森林过冬，根据第二段的第三句，第四句的提示自然选C，其余选项都是这种蝴蝶飞过的地方，但不在这些地方过冬。
(2)	解析：由最后一段可知，科学家们抓住蝴蝶做上标记，别的科学家再抓住相同的蝴蝶时，便知它们从何而来，也就判断出它们的迁飞线路了。
(3)	解析：本文的话题是黑脉金斑蝶的迁飞。（有路线，有原因都在围绕迁飞这一话题）。