Most people have a hard time studying effectively (有效地)．__16__The following are some tips on how to study effectively.
Consider the place and the time.
When you wish to study effectively，consider the place and the time.__17__You can study at the place in which you are most comfortable.This will actually help you focus as you can associate (将……联系起来) the time and place every time you study.You can actually make it a habit to study at the usual place and time.
__18_
Most of the time，people believe that coffee is the best drink to take while studying.They think coffee can actually keep them awake.It is true that coffee helps in keeping you awake，but coffee also has negative effects.__19__Water is always the best drink while studying.
Take breaks.
It is very important that you take a break before you feel tired and begin to lose your concentration (注意力) completely.Regular breaks can actually help you keep your concentration.__20_If you think you need longer breaks，then it is best that you do so.
A．Water helps a lot.
B．Arrive at school on time.
C．You are allowed to drink water in class.
D．It is always best to study at the same time and place.
E．It can slow down your memory and increase your anxiety.
F．The length of breaks may depend on the person’s ability to focus.
G．No matter how hard they try，some things always take their attention away.