变化用英语可以表示为 "change"，不变用英语可以表示为 "unchanged" 或 "constant"。

"Change" 是英文中一个常见的动词，意思是 "to make or become different"，例如：

The weather is always changing. (天气总是变化的。)
I need to change my plans for tonight. (我需要改变今晚的计划。)

"Unchanged" 是英文中一个形容词，意思是 "not altered or modified"，例如：

The price of this product remains unchanged. (这个产品的价格保持不变。)
Despite the challenges, his determination remained unchanged. (尽管有困难，他的决心依然没有改变。)

"Constant" 也是英文中一个形容词，意思是 "not changing or varying"，例如：

The constant noise was very distracting. (不断的噪音很分散注意力。)
She is a constant source of support and encouragement. (她是一个持久的支持和鼓励来源。)