First simplify and then evaluate (- x ^ 3 + x ^ 2y-y ^ 3) - (x ^ 2-2xy ^ 2 + y ^ 3) + (2x ^ 2-3x ^ 2y-2xy ^ 2), x = 2009, y = - 1 / 2, Xiao Dong mistakenly copied x = 2009 to x = 2090, but the result he got was also correct. What do you mean

First simplify and then evaluate (- x ^ 3 + x ^ 2y-y ^ 3) - (x ^ 2-2xy ^ 2 + y ^ 3) + (2x ^ 2-3x ^ 2y-2xy ^ 2), x = 2009, y = - 1 / 2, Xiao Dong mistakenly copied x = 2009 to x = 2090, but the result he got was also correct. What do you mean

Two mistakes
(-x^3+x^2y-y^3)-(x^3-2xy^2+y^3)+(2x^3-3x^2y-2xy^2)
=-x^3+x^2y-y^3-x^3+2xy^2-y^3+2x^3-3x^2y-2xy^2
=-2x^2y-2y^3
X = 2009 and - 2009, the value of x ^ 2 is the same
So he got the right result

How many days are there from December 28, 2007 to today?

749

January 7, 2006 is Saturday. What day is July 1, 2006? What day is October 9, 2006?

Saturday, Tuesday

How many days are there from August 20, 2008 to August 20, 2014

2192 days (including the first and last two days)
The program calculation is accurate