I sent the letter early that morning--- she got it that afte

in order that是表示目的,如果句子是 Isent the letter early that morning___ she can get it that afternoon。明显表示目的,答案就是in order that 。但是句子中she got it 表示过去式,不是表示目的so that 表示一种因果关系目的．比如：she is so clever that she passed the exam esailyshe worked hard so that she can pass the exam 。上面的是过去式,这里就是因果关系．