Please, could you clear up for me what is the difference in the usage of the following phrases:
once/twice... per year, once/twice... a year, once/twice.... in a year? Is it true that the first one sounds more official? Is the last one correct at all?
Thank you!
Olga
once/twice... per year, once/twice... a year, once/twice.... in a year? Is it true that the first one sounds more official? Is the last one correct at all?
Thank you!
Olga