Some people associate migration mainly
with birds. Birds do travel vast distances, but mammals also migrate. An example
is the caribou, reindeer that graze on the grassy slopes of northern Canada.
When the weather turns cold, they travel south until spring. Their tracks are so
well-worn that they are clearly visible from the air. Another migrating mammal
is the Alaska fur seal. These seals breed only in the Pribilot Islands in the
Bering Sea. The young are born in June and by September are strong enough to go
with their mothers on a journey of over 3,000 miles. Together they swim down the
Pacific Coast of North America. The females and young travel as far as southern
California. The males do not journey so far. They swim only to the Gulf of
Alaska. In the spring, males and females all return to the islands, and there
the cycle begins again. Whales are among the greatest migrators of all. The
humpback and blue whales migrate thousands of miles each year from the polar
seas to the tropics. Whales eat huge quantities of plankton. These are most
abundant in cold polar waters. In winter, the whales move to warm waters to
breed and give birth to their young.
单选题
Where can you see from the air the migration of the mammals?
【正确答案】
D
【答案解析】[分析] 细节题型。
见第三句、五句：An example is the caribou，reindeer that graze on the grassy slopes of northern Canada．．．Their tracks are so well-worn that they are clearly visible from the air．因此答案为D。
单选题
Which of the following is NOT true?
【正确答案】
B
【答案解析】[分析] 是非题型。
见文章最后一句：In winter，the whales move to warm waters to breed and give birth to their young．因此选项B为答案。
单选题
Together ______ of Alaska fur seals swim down the Pacific Coast of North America.
【正确答案】
C
【答案解析】[分析] 细节题型。
[注意本题容易选错]从文章Another migrating mammal is the Alaska fur seal． These seals breed only in the Pribilot Islands in the Bering Sea．The young are born in June and by September are strong enough to go with their mothers on a journey of over 3，000 miles．Together they swim down the Pacific Coast of North America．The females and young travel as far as southern California．The males do not journey so far．中的划线部分可知，The females and young Alaska fur seal会从the Bering Sea(白令海—北太平洋的一部分)swim down the Pacific Coast of North America直到 southern California；而The males也会从白令海南下(因为These seals breed only in the Pribilot Islands in the Bering Sea．)，只不过他们没有the females and young走的远罢了。因此选项C为答案。
单选题
Which of the following is NOT described in the passage?
【答案解析】[分析] 细节题型。
见文章倒数第三、四句：Whales eat huge quantities of plankton(浮游生物)． These are most abundant in cold polar waters．所以选项A为答案。也可用排除法：选项B指的是reindeer的习性，选项C文中未提及鲸以幼仔为生，选项 D指的是tropic water，与polar water相反；所以只有选项A正确。
单选题
How many kinds of migrating mammals are mentioned in the passage?