1.exactly:通常有作比较的对象,比如：That,I think,was exactly his aim.我认为,这正是他的目的所在.
这里就是与his aim进行对比.
又如：Exactly right.And that reason is gravity.完全正确.根本原因是地心引力.
这里是与后面的And that reason is gravit进行比较的.
2.precisely：一般作为精确的准确的讲时用在测量的场合.
当做丝毫不差的,恰好的时,指的是恰逢其时机,没有比较的意思.
比如：But that is precisely what is needed when there are so many alarming signs of overheating.不过,这恰恰是在种种警示经济过热的迹象浮现时极有必要泼的冷水.
3.accurately.意思比较单一,主要指精确的,准确的.通常用在测量或者评估,但是准确程度要比precisely低.
比如：Individuals and corporations have strong economic incentives to accurately estimate the present and future earning capacity of the land.个人和公司都有强有力的经济手段来确切估计现在和将来土地的盈利能力.
