--How often do you attend the evening classes?-, three times per week. A. On the wholeB

--How often do you attend the evening classes?
--- , three times per week.
A. On the whole
B. On average
C. Little by little
D. In all

A. On the whole(答案→)B. On averageC. Little by littleD. In all解析：短语辨析。 A整体来说； B. 普通，通常； C. 逐渐地 D.总共，合计。句意：你多久上一次夜校课程？——通常每周三次。故选B。

好好学习下