单选题 Helsinki Card (赫尔辛基卡) enables the tourists to travel free on the buses, trains and subways. Holders of the card enjoy a 70% discount on the sightseeing tour and special benefits at restaurants, theatres and concerts, as well as small gifts at department stores. The validity (有效期) of Helsinki Card is 1, 2 or 3 days. The card is sold at the Hotel Booking Centre and travel agencies.