Ответ:

1. If I had a company, I would sell plastic products.

2. If I had a company, I would advertise in the newspaper.

3. If I had a company, I would use "buy one get one for free" to promote my products.

4. If I had a company, I would be rich.

5. If I had a company, I would grow fruit and vegetables.

6. If I had a company, I would develop new promotion techniques.

Объяснение:

if + past simple; ...would + infinitive