单项选择题A．They can meet formally at first.B．They can date along with him and his girl friend.C．They can go to see a play together.D．They can make a phone call first.

单项选择题A．It can increase production by 4.5 percent in factories at least.B．It is sometimes very boring to the workers.C．It can possibly give people better feeling and influence their attitudes.D．It is always faster than any other music.