.
One every other day.
One each day.
Two each day.
It cannot be predicted.
Image A
Image B
Image C
Image D
April 2
April 4
April 6
April 8
Neap high tide.
Neap low tide.
Spring high tide.
Spring low tide.
Earth's gravity alone.
The Moon's gravity alone.
The Sun's gravity alone.
The gravity of the Moon and the Sun.