They needed a keep because that was the strongest part of the castle and the portculis.
Glucose and oxygen
it was built on two hill like things and surrounded by water that way enemies could not climb up to the castle.
Two eggs and Two Sperm.
time
the normans The people needed to build a castle would be special workers
soil and sunlight
Land & Trade
Plants and Animals!
A Square Keep Castle is an extension from a motte and bailey castleand can be called two different things, Square Keep Castle or a Stone Keep Castles. The reason from both of these names is that they were square and they were made out of stone.
Heat and pressure
Yoda and Mace Windu
Carbon Dioxide and Water