1. How to say goodbye at the end of the day to a colleague? ( "Enjoy your evening", "Have a nice night", "See you tomorrow", "Bye Bye". Any of these are common in the US.)
2. How can you say thanks to your audiences at the end of you presentation? ("Thanks for listening", "Thanks for being such an attentive audience", "Thank you so much. I really enjoyed talking to you today." Any of these will do. )
3. What would you say if you want to talk about your current working environment? (There is no short answer for this - everything depends on who you are talking to and your purpose.)
4. What would you say if you want to know the birth place of your colleague? ("Where were you born?" This is the most commonly used phrase and I have asked this of people many times. No one has refused to answer yet... :) )
5. You are in a shop. How can you ask the shop assistant about the price of a shirt? ("I don't see the price on this shirt. Can you tell me how much it is?")
I hope this was helpful. :)