单项选择题As a literary device, _______ contains at least one more layer of meaning concealed behind an explicit expression. A、image B、metaphor C、Symbol D、Both A and B.
单项选择题免疫电泳的影响因素不包括 A. 电场强度 B. 溶液pH C. 离子强度 D. 抗体纯度 E. 电渗
