题目内容：
Questionsarebasedonthefollowingpassage. Wheredopesticides(杀虫剂)fitintothepictureofenvironmentaldisease?Wehaveseenthattheynow（36）soil,water,andfood,thattheyhavethepowertomakeourstreamsfishlessandourgardensandwoodlands（37）andbirdless.Man,howevermuchhemayliketopretendthecontrary,ispartofnature.Canheescapeapollutionthatisnowsothoroughly（38）throughoutourworld?
Weknowthatevensingle（39）tothesechemicals,iftheamountislargeenough,cancauseextremelyseverepoisoning.Butthisisnotthemajorproblem.Thesuddenillnessordeathoffarmers,farmworkersandothersexposedto（40）quantitiesofpesticidesisverysadandshouldnotoccur.Forthepopulationasawhole,wemustbemoreconcernedwiththedelayedeffectsofabsorbingsmallamountsofthepesticidesthat（41）polluteourworld.
Responsiblepublichealthofficialshavepointedoutthatthebiologicaleffectsof（42）arecumulative(累积的)overlongperiodsoftime,andthatthedangertotheindividualmaydependonthesumoftheexposuresreceivedthroughouthislifetime.Fortheseveryreasonsthedangeriseasily（43）.Itishumannaturetoshakeoffwhatmayseemtousa（44）offuturedisaster."Menarenaturallymostimpressedbydiseaseswhichhaveobvioussigns,"saysawisephysician,DrReneDubos,"yetsomeoftheirworstenemiesslowlyapproachthem（45）".
A．chemicals
B．obviously
C．threat
D．pollute
E.found
F.invisibly
G.touch
H.distributed
I.sufficient
J.avoided
K.exposure
L.ignored
M.silent
N.unnoticed
O.Small
第(36)题应填__________
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