oscillate
verb [ I ] uk/ˈɒs.ɪ.leɪt/ us/ˈɑː.səl.eɪt/
来回摆动;振动;振荡
to move repeatedly from one position to another
The needle on the dial oscillated between full and empty. 刻度盘上的指针在“满”和“空”之间来回摆动。
formal（感情或看法）摇摆不定
If you oscillate between feelings or opinions, you change repeatedly from one to the other.
My emotions oscillate between desperation and hope. 我时而感到绝望，时而怀有希望。
physics specialized（波或电流）振荡
(of a wave or electric current) to change regularly in strength or direction