You can hardly imagine the difficulty the woman had __bringing up__ her children． bringing up

对的.抚养的意思语态对吗？有的答案是 to bring up, 还是 brought up ?? 请帮忙分析一下语法是bringing up 才对。这是have difficulty in doing sth，（做某事有困难）的固定搭配。the woman had difficulty bringing up her children。。。。既然是固定搭配， 为何没有介词IN 呢， 也就是说bringing up 前边是不是要加个IN呢？in可省略。