一、填空题
1. $2a - 4b - 3a + 6b =$
2. $3a^2 + 9 - a^2 - 4 =$
3. $3xy - 4xy - (-2yx) =$
4. $3a^3b^4 - 2a^5b^2 - 6a^3b^4 =$
5. $\frac{3}{5}t - \frac{2}{3}p^2 - \frac{1}{5}t + \frac{1}{3}p^2 =$
6. $xy^3 - x^3y + 3x^3y - xy^3 =$
7. $3(-ab + 2a) - (3a - b) =$
8. $14(abc - 2a) + 3(6a - 2abc) =$
9. $(3a^2 + 2a - 1) - 2(a^2 - 3a - 5) =$
10. $x + [-x - 2(x - 2y)] =$

1. $-a+2b$
2. $2a^2+5$
3. $xy$
4. $-3a^3b^4-2a^5b^2$
5. $\frac{2}{5}t-\frac{1}{3}p^2$
6. $2x^3y$
7. $-3ab+3a+b$
8. $8abc-10a$
9. $a^2+8a+9$
10. $-2x+4y$

二、化简
11. $6mn - 3m^2 + 3n^2 - 4mn + 4m^2 -5n^2$
12. $ab -7a^2b +2ab^2 -9ab +6a^2b -ab^2$
13. $7y^2 -9y -5 +4y -6y^2 +1 +5y$
14. $2xy - \frac{1}{5}x^3 -2xy +0.5x^3 -y^3$
15. $2(2a^2 -3ab) -3(-2a^2 + \frac{1}{5}ab)$
16. $3(2x^2y -xy) -4(yx^2 +xy -1)$
17. $3x^2 - [5x - (\frac{1}{2}x -3) +2x^2]$
18. $2t - [t - (t^2 -t -3) -2] + (2t^2 -3t +1)$

11. $2mn+m^2-2n^2$
12. $-8ab-a^2b+ab^2$
13. $y^2-4$
14. $\frac{3}{10}x^3-y^3$
15. $10a^2-\frac{33}{5}ab$
16. $2x^2y-7xy+4$
17. $x^2-\frac{9}{2}x-3$
18. $3t^2-3t$