3-4-1-2 Adaptations for Different Opponents: Strategies, Formations, Countermeasures

What is the 3-4-1-2 formation in soccer?

How can the 3-4-1-2 formation be adapted against defensive opponents?

What countermeasures can be employed against attacking opponents using the 3-4-1-2 formation?

Which player roles are crucial in adapting the 3-4-1-2 formation?

When should teams consider switching to a 3-4-1-2 formation?