adj.令人心烦意乱的；令人苦恼的
动词upset的现在分词形式.
I didn't mention it because I was afraid of upsetting him/afraid (that) I might upset him. 我没有提起那件事，因为我怕他心烦意乱。
The drunk was upsetting all the other customers and the landlord decided it was time to show him the door. 这醉汉使其他所有的顾客心烦意乱，因此店主决定该把他赶出门外。
How upsetting! 真叫人心里不安！
