能够激起有机体的定向行为，并能满足某种需要的外部条件或刺激物称之为( )

A．需要

B．动机

C．强化

D．诱因

用pass构成的短语完成下列句子。

①His mother___________（去世）last year．

②The procession _________right_________（经过）my front door.

③I can't__________（忽视此事）by without making a protest（抗议）．

④Knowledge_________（相传）from generation to generation

⑤He escaped by_______________（伪装成一名士兵）．

⑥I___________（把你的留言带给）my mother.