_____clearly so that your teacher_____you correctly.

A．Write, can understand

B．Having written, can understand

C．To write, could understand

D．Writing, will understand

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