酒中加入戒酒药使酗酒者饮用后痛苦的恶心呕吐,抵消了饮酒的欣快感,从而促使戒酒,这种方法是()
A.系统脱敏疗法
B.厌恶疗法
C.放松训练
D.生物反馈疗法
E.标记奖励法
参考答案:B
N型半导体中的多数载流子是( )
A.空穴 B.自由电子C.施主离子 D.受主离子
Although she doesn't like to live in the country, _______ , she goes there for a picnic. [ ]
A. once in a while
B. for a while
C. at the moment
D. from now on