Historically，humans get serious about avoiding disasters only after one has just struck them.【C1】______that logic，2006’should have been a breakthrough year for rational behavior.With the memory of 9/11still【C2】______in their minds，Americans watched hurricane Katrina，the most expensive disaster in U.S.history，on【C3】______TV.Anyone who didn’t know it before should have learned that bad things can hap pen.And they are made【C4】______worse by our willful blindness to risk as much as our【C5】______to work together before everything goes to hell；
Granted，some amount of delusion.（错觉）is probably part of the【C6】______condition.In A.D.63.
Pompeii was seriously damaged by an earthquake and the locals immediately went to work【C7】______，in the same spot until they were buried altogether by a volcano eruption 16years later.But a 【C8】______of the past year in disaster history suggests that modern Americans are particularly bad at 【C9】themselves from guaranteed threats.We know more than we 【C10】______did about the dangers we face.But it turns 【C11】______that in times of crisis，our greatest enemy is 【C12】______the storm，the quake or the【C13】______itself.More often，it is ourselves.
So what has happened in the year that【C14】______the disaster on the Gulf Coast？In New Orleans，the Army Corps of Engineers has worked day and night to rebuild tile flood walls.They have got the walls to 【C15】______they were before Katrina，more or less.That’s not【C16】______，we can now say with confidence.But it may be all 【C17】______can be expected from one year of hustle（忙碌）.
Meanwhite，New Orleans officials have crafted a plan to use buses and trains to【C18】______the sick and the disabled.The city estimates that 15，000people will need a【C19】______out.However，state officials have not yet determined where these people will be taken.The【C20】______with neighboring communities are ongoing and difficult.

【C1】（）

A．To
B．By
C．On
D．For