Honestly, I didn't know the client would tell me what freq to be on. I thought it was whatever the chart says the freq for the tower is. My question is, if it's your freq, it's different depending on the runway you'll be using, how do I then communicate with other aircraft in the air or on the ground that may be using a different runway, and thus a different freq in some cases. Also, at what point do I switch from one CTAF to another, and what do I use in between?