Onreceiptofyourinstruction,weshallcarryoutthisorder______.
WhenBobwokeuphefoundhimselfinhospital,buthedidnt__________.
若A为3阶方阵且|A-1|=2，则|2A|=()
领先指标是指那些()
Therearemanyislands______thecoastofChina.
若A为6阶方阵，齐次线性方程组Ax=0的基础解系中解向量的个数为2，则r(A)=()