观察咨询法是信息收集的最基本的方法，一般观察咨询可采用下面的哪种方式？（）
A.面谈
B.书面调查
C.电话咨询
D.隐蔽监视
参考答案：A, B, C
(2013·江西红色六校二模)________ little such material left, they decided to hold a meeting to discuss what ________.
A．There was; was done
B．Being; to be done
C．Having; to do
D．With; was done
食源性疾病的分类。按致病因子分为哪八类？
