问题

If you win the competition, you will be given _____ to Europe for two.
A:a free 7-day trip
B:a free trip for 7-day
C:a 7-day free trip
D:a trip for 7-day free;
B:a free trip for 7-day
C:a 7-day free trip
D:a trip for 7-day free;
正确答案是: