The aim of controlled scientific experiments is ______.

A．when the method of controlled experiment was first introduced
B．when Galileo succeeded in explaining how things happen
C．when Aristotelian scientists tried to explain why things happen
D．when scientists were able to acquire an understanding of reality by reasoning

A．People used to drink coffee in larger quantities.
B．It is essential to attach a separate carafe, while "drip" coffee makers are applied.
C．People used to make a pot of coffee in the morning and drink it up.
D．The new coffee makers usually cost less than befor