进军美利坚作文9.9

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The reading passage supports the bird navigation by three theories. However, the speaker in the lecture casts doubts the points with more evidence.

To begin with, the author demonstrates that birds use the sun and star as compass. But the lecture acclaims that it is not reasonable that the birds could find the direction by the sun, as in the evening the birds will not find the way but they need to fly. In addition, there is only one kind of birds use the star as direction tool, therefore, the perspective about the sun and the star is unconvincing.

Also the viewpoint of landmark features may not be one of cues for birds. The reason is that the birds should find landmark before traveling, but if birds fly through a strange place, those graphical cues seem ineffective. So the familiar objects cannot direct the birds.

The speaker acclaims that the earth's magnetic field may help birds to distinguish the north and west, but it cannot help to find the exact location. Hence, the magnetic field should not be the essential condition for birds' direction.

To conclude, the speaker in the lecture totally casts refutes the views in the reading passages concerning the bird’s navigation.