单词down-card
网络: 不翻开的底牌；牌面朝下的牌
If a face-up card can be played, the face-down card just below it is immediately turned face-up, and becomes eligible for play .
如果能打了正面朝上的牌，那么在下面的正面朝下的牌会被立即翻过来并且有资格参与。
credit card is belonged to borrow definitely write down card , " deposit money first , consume after " , deposit has breath ;
信用卡属于准贷记卡，“先存款，后消费”，存款有息；贷记卡“先消费，后还款”，存款不计息。