通过一定的榜样来强化相应的学习行为或学习行为倾向,称为()。
参考答案:替代性强化
____ four years since I joined the Army.
A.There was
B.There is
C.It was
D.It is
枕骨大孔疝,下列哪一项不是常见症状()
A.意识障碍
B.呼吸突然停止
C.头痛剧烈,呕吐频繁
D.强迫头位
E.早期出现一侧瞳孔散大