1. 时间表达方面：

大前天可以表达成“three days ago”，表示距离今天前三天的时间。也可以使用“the day before yesterday”，表示昨天的前一天。

例句：

- I last saw him three days ago.

- We went to the beach the day before yesterday.

- What did you do three days ago?

2. 简化表达方面：

大前天也可以简单地表述成“two days before yesterday”，意思与“the day before yesterday”相同。

例句：

- He called me two days before yesterday.

- The assignment was due two days before yesterday.

- I got a haircut two days before yesterday.

3. 按照工作日计算方面：

在办公场合，大前天可以按照工作日计算，表达成“three working days ago”。这个表达方式可以使人更加清晰地理解距离某个事件发生的时间。

例句：

- The report was submitted three working days ago.

- The package was shipped three working days ago.

- We received their response three working days ago.

总结：

在英语中，大前天的表达方式有很多种。除了最常见的“the day before yesterday”外，还有更加简化的表达方式，如“two days before yesterday”。在商务交流中，将大前天按照工作日计算也是一种行之有效的表达方式。具体的表达方式可以根据不同的语境和交流对象灵活运用。

五条例句：

1. She missed her flight three days ago.

她三天前错过了她的航班。

2. We had a meeting two days before yesterday.

前天的两天前，我们开了一次会。

3. The package was delivered three working days ago.

包裹已于三个工作日前投递。

4. I finished the project two days before yesterday.

前天的前两天，我完成了这个项目。

5. He called me three working days ago.

他三个工作日前给我打了电话。