fluctuate
v[I, Ipr]
~ (between A and B)
1 (of a price, number, rate, etc) rise and fall; change irregularly (指价格、 数量、 比率、 费用等)涨落, 波动
The price fluctuates between 5 and 6. 价格在5英镑与6英镑之间波动.
2 (of an attitude or a state) change continually and irregularly; waver (指态度或状态)变化不定, 动摇
fluctuating opinions 变化不定的意见.
I suggest that we ask users of this machine what they think about it. We can photograph them using it too. Then we can put their comments at the top of the advertisement in big print. We can bring in some humour too. People enjoy reading humorous ads.