询问头痛的性质与程度，主要可鉴别
A．病因
B．病位
C．病性
D．病机
参考答案：A,C,D
All the students _____two groups by the teacher during the competition.
A．were divided into
B．were divided
C．divide into
D．divided into
It's quite an informal gathering, you needn't _____ for it. [ ]
A. dress up
B. dress
C. dress on
D. dress in
