What was in a great demand in Britain after the Civil War

A．Research shows that most people are carrying a gene that allows the body to break down caffeine quickly.
B．Research shows that even some people have faster gene, they should limit the cups of coffee each day.
C．Drinking coffee will only do harm to people’s health.
D．People who have a slower gene should not drink coffee more than three cups a day.

A．It would make the workday longer.
B．It would allow people to work on the weekend.
C．It would make leisure activities expensive.
D．It would create much more free time.