- Mr Trump has been known to vacillate over great swathes of policy, but on trade he has been consistent in his belief that America gets a bad deal.
- And Mr. Trump has vacillated about what his first policy priorities will be — shifting from health care to tax cuts and back to health care — which has most likely made it difficult to plot a travel schedule that would give him a strategic advantage.
[verb] alternate or waver between different opinions or actions; be indecisive
Vacillate 一词源自拉丁语 vacillare （来回摆动；犹豫）的过去分词 vacillatus ，16世纪末进入英语后也是用来表示因缺乏平衡而不稳定地“摇摆、波动、震荡”，比如：
The earthquake caused the house built using salvaged materials to vacillate.
等到了17世纪20年代后， vacillate 开始发展出现在的主要含义指观点或立场的“摇摆、动摇、犹豫、踌躇”，常意味着因无法作出固定不变的或最终的决定而导致长时间的犹豫，诸如在不同的意见、选择或效忠对象之间来回摇摆或不停转变，比如：
Oh, do stop vacillating and make up your mind. There is no room for sentiment in business.
The volatile actress was affable at one moment, choleric the next. Her mood vacillated between hope and despair.
At the meeting celebrating the 20th anniversary of Hong Kong's return to the motherland in 2017, I stated that the central government, in implementing the principle of "one country, two systems," will maintain two key points: first, the central government will remain resolute in implementing the principle, and will not change or vacillate in this stand; and second, the principle will be implemented as what it is originally intended precisely.