单项选择题 As the number of degrees of freedom for a t distribution increases, the difference between the t distribution and the standard normal distribution A、becomes larger B、becomes smaller C、stays the same D、None of these alternatives is correct.

单项选择题 7.2 如果是椭圆偏振光经过偏振片，旋转偏振片360度将观察到与部分偏振光相似的现象。

问答题 选择一家当地的奶制品企业，采用SWOT分析讨论其市场状况，按照创意的步骤，沿着营销活动的前、中、后期进行创意，形成策划创意方案。