He hurried to the booking office, only ________ that all the tickets had been sold out.

A．to tell

B．to be told

C．telling

D．told

新疆绿洲边缘的环境非常脆弱，对_______的破坏和_______的不合理利用，将很容易导致土地荒漠化和盐碱化，并逐步成为沙漠。