x3+2xy-x-xy2.
原式=x(x2+2y-1-y2)
=x[x2-(y2-2y+1)]
=x(x+y-1)(x-y+1).
-I missed the first part of ________ film Avatar.
-What a pity ! You should be here half _______ hour earlier.
A.a, the
B.a, an
C.the, a
D.the, an
单体液压支柱的寿命规定为5年。