有效的强化物应具有的特点是()
A.不需要花费大量时间
B.多次使用不至于引起迅速的饱和
C.积极强化实施过程
D.易用
E.以上都对
参考答案:E
---She’s never been to Shanghai, ____________? .
--- ___________. But how she wishes to go there again.
A.is she, Yes
B.is she, No
C.has she, Yes
D.has she, No