学生回答问题后教师没做任何评价,学生以后不再举手回答问题,这种现象是()。
A.正强化
B.负强化
C.惩罚
D.消退
参考答案:D
.
When we were young, we were brought up by our parents to _______ the table manners both at home and in public.
A.determine
B.observe
C.announce
D.control
工程质量标准属于()标准。
A.行业标准
B.企业标准
C.技术标准
D.管理标准