阅读理解 (共20小题：每小题2分，满分40分)

　　The sky usually looks light blue. But if you went to the top of the highest mountain， went to the top of the highest mountain， where there is less air between you and the sun to scatter the sunlight， the sky would be deep， dark blue. And if you rode in a rocket high above the earth， where there is no air at all to scatter the sunlight， the sky would be so dark that it would be black. Sometimes the sky doesn't look blue. At sunrise and sunset， the light from the sun sometimes is scattered in such a way that you see red， orange， and other colors in the sky. 65. The sky usually looks light blue because _____. A. the sun is light and blue B. the air is light and blue C. the air scatters the sunlight D. the sunlight is blue 66. The sky looks dark blue when _____. A. there is less air between you and the sun B. there is high mountain C. the mountain is highest D. you climb a mountain

　　67. The sky looks black if ______.

　　A. you ride in a rocket

　　B. the rocket is high in the sky

　　C. the rocket is high above the earth

　　D. there is no air to scatter the sunlight

　　68. Sometimes the sky doesn't look blue because ______.

　　A. the sun is rising B. the sun is setting

　　C. the air has different colors

　　D. the light from the sun is scattered in a different way

　　69. A good title for this passage would be _______.

　　A. The Sky Looks Blue

　　B. Why the Sky Looks Colorful

　　C. The Beautiful Sunlight

　　D. Something About the Air