在混凝土施工中，统计得出混凝土强度标准差越大，则表明混凝土生产质量越不稳定，施工水平越差。
参考答案：对
—Where did you have the discussion with Professor Snow?
—It was in the classroom ________ we had a biology lesson yesterday.
A．which
B．when
C．that
D．where
斯氏并殖吸虫病最有意义的诊断方法是
A．皮下包块找到童虫
B．痰液中找童虫
C．皮下包块找虫卵或成虫
D．体液中找虫卵
E．粪便中查虫卵
