问题

For many years we have been keepingin ____by sending each other e-mails or phone calls
A:There’s a connection between violence and sports
B:One cause of violence at sports events is alcohol
C:There are many reasons for violence at sports events
D:was working
B:One cause of violence at sports events is alcohol
C:There are many reasons for violence at sports events
D:was working
正确答案是: