cross指的是交叉的意思
across是穿过的意思
through是穿越的意思
across与 cross只是在拼写相近，但意思是不同的
across与through在意思上倒是很接近的
across一般指的是穿过马路　across the street
through则指的是距离比较长的　through the forest
across prep. 平面穿过（立体的用through e.g. run across the street, look through the window,go through the forest）
cross v. 与across向对应，可直接加名词
意思差不多，给你个例子；

McDonalds is located across the street: 麦当劳在马路对过

If you cross the street, you will get there:过了马路就到了

You have no idea what I had to go through for the past couple of years:你可不知道我这几年都经过了些什么

Through the good and the bad, I realized that I have matured significantly；经过好的坏的，我发现我已成长了很多

you crossed the line: 你越线了.



参考文献：http://ks.cn.yahoo.com/question/1406062006672.html