6. Complete with the Past continuous or Past simple. Example: It (get) was getting cold, so we (go) went back home. A) They (play) ... in the sea when they (see) ... the treasure.

A) They were playing in the sea when they saw the treasure.

Past continuous используется для длительного действия, происходившего в момент другого события, а Past simple — для краткого завершённого события.