要研究家长对子女上大学的态度,最适宜的方法是( )
A.观察法
B.预测法
C.实验法
D.调查法
参考答案:D
—What were you doing at six yesterday evening?
— I _____ in the kitchen. [ ]
A. cook
B. cooked
C. was cooking
D. have cooked
猩红热的病原菌为()
A.A族乙型溶血性链球菌
B.A族甲型溶血性链球菌
C.A族丙型链球菌
D.草绿色链球菌
E.金黄色葡萄球菌