单项选择题

The main idea of the first paragraph is that ______.

A．people traveled on lakes thousands of years ago
B．people used logs thousands of years ago
C．traveling was hard thousands of years ago
D．there were no roads and cars thousands of years ago

<上一题目录下一题>

热门试题

单项选择题

By his outdoor cousins the author means ______.

A．other experimenters
B．B ) the other doves of the same brood
C．doves under the natural sky
D．other birds in general

单项选择题

The experiment with the dove indicated that ______.

A．birds have to be taught to navigate
B．a bird that has been caged will not fly long distances
C．some birds cannot fly at night
D．some birds seem to follow the stars when they fly at night