Food and guns were difficult to find to keep the Confederate armies in the field.

VOA: special.2009.10.22

Self learners have also told us that they are OCW eager to come to OCW often in order to keep current and the latest thinking in their field.

自学者告诉我们,他们渴望每天经常浏览,以便查询他们领域的最新思想。

麻省理工公开课 - 媒体、教育、市场课程节选