设想迪邦只是从我们所在的位置跨过大海的简短的行程.
1）本句没有主语和谓语,动词不定式短语直接引导出后面的内容,即主体结构是：To think something(这里同位语that代表的后面的整句相当于something,即Dipan is only a short journey across the sea from where we are..)
2）后面的子句当中,即Dipan is only a short journey across the sea from where we are..当中,where we are..是状语从句,相当于我们所在的位置.如果你在大连,该句可以换成更容易理解的：Dipan is only a short journey across the sea from Dalian.