If you learned English as a second language, which letters or combinations of letters proved most difficult ?

Question

If you learned English as a second language, which letters or combinations of letters proved most difficult ?

Answer 1

I don't remember any of them being particularly complicated, other than the sound th was hard.

Answer 2

Th. That sound is very difficult :)

Answer 3

For me the "dl" is impossible to pronnunciate.

For example: Supposedly

Impossible!