I got stuck in traffic again.
"be/get stuck"就是指陷入,受困于某种不愉快的境遇中.be/get stuck in traffic是遇上堵车的常见表达.
We were stuck in traffic for over an hour. 我们遇上堵车,堵了一个多小时.
I hate being stuck at home all day. 我讨厌整天困在家里出不去.
I feel bad about how much my car is adding to the pollution problem in this city.
"add to sth"的意思就是"使(数量)增加,使(问题)规模扩大"的意思, to increase something in size, number, amount, etc.
The bad weather only added to our difficulties. 恶劣的天气只是增加了我们的困难.
The house has been added to(= new rooms, etc. have been built on to it)from time to time. 这座房子一次又一次地在扩建.
这里相当于"contribute to".