A-A+
A．There is still no exact explanation up to no
问题详情
A．There is still no exact explanation up to now.
B．The birds have the acute sense about the weather.
C．The birds can tell it from the moving of the sun.
D．The other birds in the flock send the information.
参考答案
正确答案：A
解析：题干询问鸟类如何判断出什么时间迁徙过冬。文章中的论述为：How do they know when it is time to leave for the winter? Scientists are still studying this．由此推测该问题还没有确定的答案。
