关于“压力山大”的成人英语表达，综合多个来源的信息，可以总结如下：
一、常用翻译
核心短语 - Under a lot of pressure
- Feeling overwhelmed
- Under great stress
- Very stressful
- With a lot of pressure
完整句子示例
- I'm under a lot of pressure at work right now.
- The project deadline is looming, and I feel overwhelmed.
- This situation is causing me a great deal of stress.
- The workload is so heavy, it's very stressful.
二、表达建议
避免混淆
- Stress（如 under stress）多指内在情绪压力，例如：
> I've been feeling stressed lately because of the changes.
- Stressful（如 a stressful job）用于描述事物本身具有的压力属性，例如：
> This job is really stressful, but I'm learning to cope.
- Pressure（如 pressure on performance）常指外界施加的客观压力，例如：
> The company is putting too much pressure on employees.
地道化表达
- 使用比喻手法增强表达效果，例如：
> The meeting room was packed, making me feel like a fish out of water.
- 结合具体场景描述压力来源，例如：
> Balancing work and family life has become a real challenge.
三、补充说明
非标准翻译： "压力山大"被音译为 "Alexander"
在日常交流中，可直接说 "I'm feeling a bit overwhelmed"或 "This is too much"，更符合英语母语者的表达习惯。
通过以上方法，可以更准确、地道地用英语表达"压力山大"的含义。