问题详情

THE AIRPORT EXPRESS DEPARTS FROM PLATFORM. 3 EVERY 20 MINUTES DURING THE DAY (EVERY 30 MINUTES AT NIGHT)
A．The train service to the airport runs 24 hours a day.
B．Airport trains leave Platform. 3 at 20 minutes past the hour.
C．The airport express takes half an hour at night.请帮忙给出正确答案和分析，谢谢！