英文：what is the difference between primary sources and second
问题描述：
英文：what is the difference between primary sources and second
请用英文回答,是历史题,在美国,老师要主要来源和次要来源之间的区别是什么
答
A primary source is a document or physical object which was written or created during the time under study. These sources were present during an experience or time period and offer an inside view of a...