二阶系统的特征方程为a0s3+a1s2+a2s+a3=0,系统稳定的主要条件是各项系数的符号必须( )。
A.小于零 B.大于零 C.等于零 D.小于1
参考答案:B
下列改革中,实现了富国强兵,“倾邻国而雄诸侯”的是
A.商鞅变法
B.汉武帝改革
C.北魏孝文帝改革
D.王安石变法
The way she dealt with the problem is quite different _______ her parents were used to.
A.from which
B.in what
C.in which
D.from what