【例文】
This month millions of American kids can forget about classroom bells and set off for grandparents' homes，sleepaway camps and lifeguard stands.But summer vacation hasn't always been a birthright of U．S.schoolchildren.Before the Civil War，schools operated on one of two calendars (日历)，neither of which included a summer vacation.Rural (农村的)schooling was divided into summer and winter terms，leaving kids free to help with the farm work in the spring planting and fall harvest seasons.Urban students，meanwhile，regularly had as many as 48 weeks of study a year，with one break per quarter.
What did the rural school calendar before the Civil War allow children to do?
A．Enjoy a summer vacation.
B．Take a break each quarter.
C．Have 48 weeks of study a year.
D．Assist their parents with farm work.
