不一定的英文

not necessarily

not neccessarilynot for sure/certaindon't count on it

That depends~~(>^ω^<)

may notEG.YaoMing may not the tallest man in china

uncertaintymaybe not benot necessarily例：Every rascal is not a thief,but a thief be a rascal.每个无赖不一定是盗贼;每个盗贼必定是无赖。Let's eat now and maybe we could catch a movie later. 咱们现在就吃,说不定吃完能赶场电影.Clouds do not necessarily forecast rain.云层未必预示下雨。

Not necessarily或者necessarily都行，还是not necessarily比较准确点儿。呵呵！

It depends. 这句直接翻译是“不一定”、“看情况”，可能更接近你想要的用法。

It depends.

not always