"Want to ask, one family of three persons, does it buy only one ticket for Expressway? Do we need to purchase extra tickets?"

You need to buy a ticket fast pass and also you need to buy 3 tickets for one person, one per person.
You need to buy a ticket, and TurboPass needs one for each person. A family of three means they need three tickets each.
One family, three people. Each person needs to buy one ticket and one Express Pass separately. Hot projects are recommended to buy an Express Pass. Three items of Express Passes would be enough.

Each person buys individually.
You need to buy a ticket and also need to buy 3 copies, one for each person.
You need to buy a ticket, VIP pass requires one per person, three people in a family would require three.
One family, three people. Each person needs to buy one ticket and Express Pass separately. Popular projects are recommended to buy an Express Pass. Three items of Express Pass are enough.

Everyone is buying individually.