To Be
#1) We are going to the United States tomorrow and we will be back in two weeks.
#2) My husband left three hours ago to buy milk and he isn't back yet.
#3) When I'm back from my trip, I will call you.
#4) I heard that Tom and Sally are back together. (return to a relationship)
#5) How does it feel to be back? It's good to be back.
To Go
#1) I loved Holland and I plan to go back next Summer.
#2) She will go back to her hometown to care for her sick mother.
#3) I forgot my textbook, so I have to go back to school.
#4) Marie went back to her old job because they offered her more money. (return to a job)
#5) I will never go back to my husband. (return to a relationship/marriage)
#6) I wish I could go back in time and change the past.
To Come
#1) I'm leaving now, but I will come back in an hour.
#2) My roommate came back very late last night and he wasn't alone.
#3) Come back! I'm so lonely without you. (return to a relationship)
#4) I asked for my job back, but they said that there's no job to come back to. (return to a job)
Other
#1) Welcome back! How was your trip?
#2) Get back in line! (military / school / prison expression)
#3) He lent me his car and he took it back the next day.
#4) Stay back! I will jump off this building. (Don't come closer to me! -- suicide expression)
#5) We had to walk back home because our car broke down.
#6) I take back everything I said. (I said something, but I want to un-say it.)
#7) We drove around the city for two hours before we turned back.
#8) Give me back my guitar!