持卡人事先在发卡银行存款，持卡购物、消费时以存款余额为限度的银行卡是()。
A．贷记卡
B．准贷记卡
C．借记卡
D．透支卡
参考答案：C
阅读短文，回答问题。
Today is Sunday. Amy and her friends are in a village. The village is beautiful. There are many rivers and
bridges in the village. The water is clean. The air is fresh. There are many mountains near the village. They are
very happy.
1. What day is it today?
___________________________________________
2. Where are they?
3. What are near the village?
4. Is the air fresh?
在人群或动物中进行实验，观察在增加或消除某因素后疾病发病率的变化（）
A.描述流行病学
B.分析流行病学
C.实验流行病学
D.理论流行病学
E.血清流行病学
