求帮忙分析一个英语句子··谢谢

题目

求帮忙分析一个英语句子··谢谢
David Laird says many of his schools would like to reduce their merit aid but fear that in doing so,they would lose top students to their competitors.
我要问的是in doing so放这里怎么讲,我觉得是多余的啊?
是代指前面的么?为什么是doing?
为什么有逗号?

答案

doing 是动名词,介词后面的动词必须是动名词形式.in doing so就是“这样做”,在这里不能省略.逗号后面是另一句话.
整句话意思是“大卫.莱尔德说,他的许多学校都希望减少助学金,但却又担心这样做,因为他们也许会把最优秀的学生赶到自己竞争对手那里去.”