Slavery was () in Canada in 1833, and Canadian authorities encouraged the slaves, who escaped from America, to settle on its vast virgin land.

A．diluted

B．dissipated

C．abolished

D．resigned

切牙乳突作为无牙颌解剖标志的作用是

A．确定平面的标志
B．排列上颌中切牙的参考标志
C．确定基托伸展范围的标志
D．确定牙槽嵴顶的标志
E．确定后堤区的标志