1) ______ the theory of language underlying the communicative approach
2) ______ the theory of learning underlying the communicative approach
3) ______ one of the objectives of the communicative approach
4) ______ one of the techniques of the communicative approach
5) ______ one of the main features of the communicative approach
a) language best learned through use in social context
b) to develop the students communicative competence
c) role play
d) the introduction of authentic texts into the learning situation
e) functional linguistics

对慢性疾病进行现况调查，最适宜计算的指标为

A．罹患率

B．发病率

C．患病率

D．感染率

E．发病比