Before the age of the Internet, we used to ____ our holidays through travel agents. A: Book B: having booked C: ooking D: have booked

Before the age of Internet, we used to _________our holidays through travel agents. A: ook B: ooking C: having booked D: have booked

海运托运单是__。 A: letter of credit, L/C B: ooking note, B/N C: ill of lading, B/L D: sales contract,S/C