vacillate

1. V-I If you vacillate between two alternatives or choices, you keep changing your mind. 猶豫不決[正式]

She vacillates between men twice her age and men younger than she. 她在兩個男人之間搖擺不定，一個年齡比她大一倍，一個比她小。

We cannot vacillate on the question of the party's leadership. 在黨的領導權問題上我們不能動搖。