描述性口腔流行病学最常用的方法是
A．纵向研究
B．横断面研究
C．抽样调查
D．随机分组调查
E．纵向研究和横断面研究
参考答案：E
— Alison, I'm sorry. I can't come to the wedding with you tomorrow morning.
— ______?
— My grandma was severely ill, so I have to stay in the hospital to look after her. [ ]
A. How is it
B. How come
C. So what
D. What's the problem
福利应以全体员工为对象，这体现了员工福利管理的 ( )
A．合理原则
B．量力而行原则
C．统筹规划原则
D．公平的群众性原则
