—How shall we go to the airport?
—Let’s take the airport bus. It ______ only 20 minutes and ______ much less than taking a taxi.
A. takes；costs B. spends；spends C. spends；costs    D. takes；spends

—There ________ lots of trees in the area.
—But they have all gone because people built a railway here.

A．have been

B．used to be

C．have had

D．used to have