The children often go swimming on Sundays. They have much free time then.

A. The children often go swimming on Sundays when they have much free time.

B. The children often go swimming on Sundays on that day they have much free time.

C. The children often go swimming on Sundays where they have much free time.

D. The children often go swimming on Sundays which they have much free time.

Luyện tập mệnh đề quan hệ (2)