已知方程3x+a=2的解是5,则a的值是( )
A.-13
B.-17
C.13
D.17
将x=5代入方程3x+a=2中得:15+a=2
∴a=-13.
故选A.
4.______in his office work, he had no time to attend to his sick daughter.
A.Kept engaging
B.Kept engaged
C.Keeping engaging
D.Keeping engaged
对配作加工的凸、凹模,其零件图无需标注尺寸和公差,只说明配作间隙值。