He_______ his students lessons though he was not feeling well.
A:insisted on giving
B:insisted to give
C:insisted to giving
D:insisted given
如图,已知△ABC三个内角的平分线交于点O,延长BA到点D,使AD=AO,连接DO,若BD=BC,∠ABC=54°,则∠BCA的度数为____°.
下列关于物质的性质和用途说法不正确的是( )