原式=(x+1)(x-1)x-1•2xx(x+1)2
=2x+1，
当x=-2时，原式=2-2+1=-2．
根据提示,以My Winter Vacation 为题写一篇50-60词的作文。
提示：今年寒假，我打算去昆明度假，呆一个星期。我打算钓鱼、游泳、观光、赏花。我乘飞机去，希望我的假期过得愉快。
一 Why didn't you remind him of the possible danger?
一 But what _____ otherwise? He never listens to me. [ ]
A. could I do
B. could I have done
C. should I do
D. must I have done
