线性方程组的初等变换移植到矩阵上,就得到矩阵的(1)____,再将(1)推广,就得到矩阵的(2)____,(1)和(2)合称矩阵的____。
方程组消元的过程也就是把方程里某些未知数的系数变为____(填数字)的过程。
A simplified mechanical _____ has an inlet and an outlet valve .
A. pump
B. filter
C. tank
D. case
The end of the rocker arm is operated by an eccentric on the______.
A. crankshaft
B. camshaft
C. countershaft
D. input shaft