Expressions to Show Attention to the Speaker

Showing attention to the speaker
Really?, Hmm..., wow!, I see, And then?, how it happen?, that's awesome!, tell me more!

Example:
Arlan : I love Adelaide City in South Australia.
Mendi : Really? Why?
Arlan : Yes, because I meet many friendly people there and the city is very clean, comfortable and it has many parks.
Mendi : wow, that's nice.
Arlan : Yes, you'll love it too.