设A为3阶矩阵，为A的属于特征值1的线性无关的特征向量，为A的属于-1的特征向量，则的可逆矩阵P为（）
SinceWilliamhadbeenseriouslyillforseveralmonths,hisparentswereworriedabout________toreturntoschoolfull-time.
Thedirectorrecommendedthatshe________(study)moreEnglishbeforegoingabroad.
Heaskedmewhethermybrother________(fly)toBeijing.
设A，B=,则A与B=（）
