They have made up their mind to stay in Britain.They have made up their minds to stay in Britain.They have made up their mind to stay in Britain.They have made up their minds to stay in Britain.这两句那句对,我觉得是第一句,因为make up o

They have made up their mind to stay in Britain.They have made up their minds to stay in Britain.They have made up their mind to stay in Britain.They have made up their minds to stay in Britain.这两句那句对,我觉得是第一句,因为make up o
They have made up their mind to stay in Britain.They have made up their minds to stay in Britain.
They have made up their mind to stay in Britain.
They have made up their minds to stay in Britain.这两句那句对,我觉得是第一句,因为make up one's mind是固定搭配,这里面mind应该是不可数,

They have made up their mind to stay in Britain.They have made up their minds to stay in Britain.They have made up their mind to stay in Britain.They have made up their minds to stay in Britain.这两句那句对,我觉得是第一句,因为make up o
mind做主意,意见的意思用时是可数的,做心智,理智等的意思时是不可数.而make up one's mind中的mind是主意的意思.所以应是make up their minds

第二句是对的

their是复数 所以mind也是复数