题目内容：

The story of Lewis and Clark's travels up the Missouri River and on to the Pacific Northwest is one of the great stories of American exploration.请问在这个句子中,怎么理解 Lewis and Clark's travels up the Missouri River and on to the Pacific Northwest ,特别是 on to……的用法,

优质解答

I am on to you 的意识是：我盯上你了
自己理解吧,不解释