答案与解析:(1988+1986+1984+…+6+4+2)-(1+3+5+…+1983+1985+1987) =1988+1986+1984+…+6+4+2-1-3-5… -1983-1985-1987 =(1988-1987)+(1986-1985)+…+(6-5)+(4-3)+(2-1) =994.