（）是目前较为广泛地用于治疗各种恐怖症且收效理想的技术。
A.强化技术
B.系统脱敏法
C.理性情绪疗法
D.认知预演
参考答案：B
Having finished lunch, the case was discussed.()
A. they discussed the case
B. they had discussed the case
C. the case was discussed
D. the case had been discussed
简述电除尘的工作原理？
