A.He’s a nice teacher
B.Ms Smart is a nice teacher
C.She’s a nice doctor
A.正强化
B.负强化
C.惩罚
D.自然消退
A.Mike, this is my brother, Sam
B.Sam, this is my brother, Mike
C.Sam, Mike, this is my brother
A.The parrot is very naughty
B.The parrot is very cute
C.The parrot is bad
A.My uncle often go fishing
B.My uncle often goes fishing
C.My uncle often went fishing