A lunar eclipse occurs when the Moon passes directly behind the Earth into its umbra (shadow). Solar eclipses occur at New Moon, when the Moon is between Earth and the Sun. Lunar eclipses are more common. It's simply a matter of the sizes of the shadows: A lunar eclipse is the result of the Earth casting a shadow on the Moon.
To the first problem : A lunar eclipse Occurs when the Moon passes directly behind the Earth, so only when the sun, Earth, and moon are aligned ; occur at full moons.
A solar eclipse Occurs when the Moon is between Earth and the Sun; Occurs at a new moon.
Lunar eclipse are more common.
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For the 2nd part:
The gravitational attraction of the moon causes tides.
One importance is Commercial and recreational fishermen use their knowledge of the tides and tidal currents to help them improve their catches
The United States has a smaller population than China, but has a higher per capita greenhouse gas emission, resulting in a larger carbon footprint on a national level.
