This is not possible with Airtable's forms, because Airtable doesn't offer dynamic filtering yet. But you can get this functionality from Fillout's advanced forms for Airtable.

Well, I tried, and I see it has the same functionality. because what I need to do is when the user picks a sector I need to only show the dates set for that sector. Not all dates. Is that possible with Fillout?

Yes, that is correct. You can dynamically filter linked record fields in Fillout.

How can i Do that. 

table 1: companies

company 1 - sector 1

company 2

table 2: sector

sector 1 

sector 2

table 3: dates. 

date 1  -- sector 1

date 2 -- sector 1

date 3

I want to pick sector 1 and only see company 1. and choose only date 2 or 3 . 

Here you go:
How to select and filter Airtable linked records in a dropdown

p.s. If your company has a budget for your project and you’d like to hire an expert Airtable consultant to help you with any of this, please feel free to contact me through my website: Airtable consulting — ScottWorld

Awesome! the tutorial Helped a lot! Thanks.