下列哪组食物不能反映欧洲西部的农业结构[ ]
A．牛排、面包
B．奶油、火腿
C．香肠、米饭
D．熏肉、奶酪
答案：C
It was in the lab________was taken charge of by Johnson________they did the experiment. [ ]
A. where; which
B. which; that
C. which; which
D. that; which
以下概念中不是常用反映流行强度指标的是：（）
A.突发
B.散发
C.流行
D.暴发
