常用于研究传染病感染状况的指标是
A．患病率
B．感染率
C．引入率
D．发病率
E．续发率
参考答案：B
It was suggested that everyone ___ in the homework on time.
A．hand
B．would hand
C．handed
D．should be handed
1g脂肪在体内完全氧化产生的能量是______。
A．4KcalB．5kcalC．7kcalD．9kcal
