SUN, MOON AND EARTH
The moon has to be in between the Sun and the Earth.
On a solar eclipse, the Sun, Moon and Earth are aligned in a way that half of Earth does not receive light for the fact that the moon is covering it.
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B. sexual selection, which alters allele frequencies in the gene pool.
C. When you take a step, the ground pushes back on your foot with the same amount of force. If it pushed back with less, your foot would go through the floor; if it pushed back with more, it would actually push your foot off the ground. But they're in opposite directions; your foot pushes down, while the ground pushes up.
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