How to avoid silence in English conversations

Sometimes you don't know what to say in a conversation. Perhaps you don't have any words to express yourself, or you haven't understood the other person. Or perhaps there isn't anything left to say! In all these situations, it's important to avoid being silent, so here are some words and expressions to use.
When you don't understand
"Sorry, I don't understand.""Sorry, could you repeat that?""Sorry? I didn't get that."
Looking for words to express yourself
You don't want to be completely silent, but you need time to find the words.
"Well…""OK…""So…"
You can even make some "noises"
"Hmmm…""Uh-huh""Umm…"
To agree with the other person
You want to show that you agree, but you don't have anything else to say.
"Yeah.""Right."
To change the subject
You've all given your opinion, and now you want to talk about something else.
"Anyway,…""Well, as I was saying…""So, back to …""So, we were saying …"