题目内容：
Acupofcoffeeinthemorningmayimprovelong-termmemory,accordingtoanewstudy.
Thestudy,publishedinthejournalNatureNeuroscience,foundthatpartici-pantswhohadbeengivencaffeine(咖啡因)pillshadbettermemory（1）Scientistsstudied160participantsaged18to30,andshowedthem（2）photos
ofitemsatthebeginning,askingstudysubjectstoclassifytheitemsas"indoor"
or"outdoor".Halftheparticipantsweregivenacaffeinepillafterthat（3）,the
otherhalfaplacebo(安慰剂).Onedaylater,alltheparticipantswereshownthe
samepictures,aswellassometheyhadn'tseenbefore.Theywereaskedwhether
eachphotowasnew,oldor（4）totheoriginals.
Whilebothgroupswereableto（5）betweenoldandnewpictures,theresearchers（6）discoveredthattheparticipantswhotookthecaffeinepillswerebetteratdeterminingwhichpicturesweresimilartothefirstround.Theresearchersremain（7）abouthowcaffeinemayinfluencememory,buttheyspeculatethatitcouldinterferewithhormones(荷尔蒙，激素)relatedtomemorymaking.
Thestudyneedstoberepeatedbeforeanyprovenconclusionscanbemade,butit'snotthefirsttofindbenefitsincaffeineintake(摄取).Infact,similarfindingsweremadeinapopulationofbees,whichleadsresearcherstobelievethatthecaffeineplayeda（8）inimprovingrecallstill,highlycaffeinatedproductshavebeenlinkedto（9）eventslikepoorsleep.In2012,theU.S.FoodandDrugAdministrationannounceditwaslookingintothesafetyofenergydrinksafter（10）severalreportsofillnessesandevendeathsaftertakingenergydrinks.
A．classification
B．conceiving
C．disguise
D．distinguish
E．Negative
F．Recall
G．Receiving
H．Remind
I．Role
J．Significance
K．Similar
L．Surprisingly
M．Temporarily
N．Uncertain
O．Various
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