完形填空!Climate change is one of the most fundamental challenges ever to confront humanity.Its impacts are already showing and will intensify over time __21__ left unchecked.There is overwhelming scientific evidence,__22__ shown in the Fourth Assessment Report (第四次评估报告的综合报告)of the Intergovernmental Panel on Climate Change (IPCC) 政府间气候变化专门委员会(IPCC),that climate change will threaten __23__ growth and long-term prosperity,as well as the very survival of the most vulnerable populations.IPCC projections indicate that if emissions continue to rise at their current __24__ and are allowed to double from their pre-industrial level,the world will face an average temperature__25__ of around 3°C this century.Serious impacts are associated __26__ this scenario (情景),including sea-level rise,shifts in growing seasons,and an __27__ frequency and intensity of extreme weather events such as storms,floods and droughts.The United Nations Climate Change Conference in Copenhagen in December in 2009 offers a __28__ opportunity to step up international action on climate change.A Copenhagen deal is __29__ the global transition into green economic growth,and,most urgently,to help the world,especially the most vulnerable,to adapt to impacts __30__ are now inevitable.单选题A..ifB..whetherC..whenD..which单选题A..becauseB..asC..whileD..when单选题A..economicsB..economicalC..economyD..economic单选题A..speedB..rateC..paceD..rhythm单选题A..risingB..riseC..raiseD..raising单选题A..withB..toC..fromD..in单选题A..being increasedB..increasedC..increaseD..increasing单选题A..historyB..historicalC..historicD..historically单选题A..necessaryB..inevitableC..essentialD..basic单选题A..thatB..of whichC..whoD..what