KTC切丝机正常生产时,当来料发生变化时,油缸液压部分的油压和流量(),刀门高度随之变化。
A、随之变化
B、增大
C、减小
D、不变
参考答案:D
抛物线y=x2+bx+c向上平移2个单位,再向左平移4个单位,得到抛物线y=x2,则b与c的值分别为( )
A.6,4
B.-8,14
C.-6,6
D.-8,-14
A number of books ______ been stolen from the library since the beginning of this term and the number _____ as large as 500.
A.have; are
B.has; is
C.has; are
D.have; is