The cycle of phases has an average period of 29.53... days (rounded).
If the moon is full tonight, then it will be full again in 59.06 days.
59.06 days is 8 weeks and 3.06 days.
Does that fit what you mean by "about" 8 weeks ?
locks. They raise ships to the water level of the differeny body of water that will be entered.
The answer is C because they show territory gained through the years
