What are the meanings of the four sentences below?
When it comes to the sense of making something the central person/thing, the verb centre bothers me. Because I'm not sure if this verb would
change the meaning of a particular sentence when the verb takes turn to be in an active voice and to be in a passive voice or it would
remain the same meaning.
At first, I thought that...
Subject(a) centres on/around object(b) would mean Subject(a) makes object(b) the central person/thing.
and Subject(a) is centred on/around object(b) would mean Subject(a) is made as the central person/thing by object(b).
... but now I think my explanation was wrong because the following two pairs seem to go against my understanding.
1a. Her research centres on the social effects of unemployment
1b. Her research is centred on the social effects of unemployment.
2a. Leisure activities largely centred around the family
2b. Leisure activities were largely centred around the family.
So What are the meanings of the above four sentences?