英语翻译：我们楼下有一家超市.我们楼下开了一家超市.

We have a supermarket downstairs. We opened a supermarket downstairs.

there is a supermarket downstairs. A supermarket is opened downstairs.(后一句相当与改被动)

here is a supermarket downstairs. We opened a supermarket downstairs.

There is a supermarket at the foot of our building.
我觉得两个句子差不多啊。都可以用这句话说。

There is a supermarket downstairs.都可以.但如果是一定要具体强调“有”和“开了”之意,后一句可以这么说：Somebody opened a supermarket downstairs.