His disappearance(失踪)______ by the police.

A．looked at

B．will be looked in

C．is being looked into

D．has been looked up

（）否认遗传在个体成长中的作用，认为一切行为都是刺激—反应的学习过程，是由环境和教育塑造出来的。

A.成熟势力说

B.行为主义观

C.精神分析论

D.相互作用论