矩阵的秩等于()。
A.1
B.2
C.3
D.4
参考答案:C
解析:
因为题干中矩阵为3×4矩阵,则0≤r≤3,该矩阵其中一个3阶子式=-32≠0,所以该矩阵的秩为3。
It's _____ today. The radio says it won't stop raining until next week. [ ]
A. fine
B. wet
C. windy
D. cloudy
小型V型铁一般用中碳钢经()加工后淬火磨削而成。
A.刨削
B.车削
C.铣削
D.钻削