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甲种燃料的热值小于乙种燃料的热值,下列说法正确的是( )
________ is the first month of a year.( )
已知整数 a1,a2,a3,a4,…满足下列条件:a1=0,a2=﹣|a1+1|,a3=﹣|a2+2|,a4=﹣|a3+3|,…,依此类推,则a2017的值为( )