下列四个图案,其中轴对称图形有( )
A:0个
B:1个
C:2个
D:3个
直线y=kx+b与曲线y=x3+ax+1相切于点(2,3),则b的值为( )
What are good questions ______a conversation?
Health problems are closely connected with bad eating habits and a________of exercise.