去括号：1.2-（1+x)+(1+x+x2+x3)2.2a-3b+{4a-(3a-b)}3.3b-2c-{-4a+(c+3b)}4.(3x4-x3+3x)+2(5x4+3x2-7x)5.(2x-3y)+(5x+4y)6.(8a-7b)-(4a-5b)7.a-(2a+b)+2(a-2b)8.3(5x+4)-(3x-5)9.(8x-3y)-(4x+3y-z)+2z10.-5x2+(5x-8x...