D．o you know how to study better and make your study more effective(有效率的)? We all know that Chinese students usually study very hard for long (11) ．This is very good，but it doesn't (12)a lot，for an efficient student must have enough sleep，enough food and enough rest and exercise． Every day you need to go out for a walk or visit some friends or some places． lt' s good for your study．

When you return (13) your study，your mind will be refreshed and you'll learn more (14) study better． Psychologists(心理学家)(15) that learning takes place this way． Here takes English learning (16) example． First you make a lot of progress and you feel happy． Then your language study seems (17) the same，so you will think you're learning (18) and you may give up． This can last for days or even weeks，yet you needn't give up． At some points your language study will again take another big (19) ． You will see that you really have been: learning all long． lf you get enough sleep，food，rest and exercise，studying English can be very． effective and (20) Don-t give up along the way learning slowly and you're sure to a

good result．( )11．

A．days

B．time

C．hours

D．weeks