Ⅰ.单项填空
1._______ the computer _______ only used in several big cities.
A.At a time;was B.At one time;was
C.One time;is D.At times;will be
2.You"d better _______ a plan _______ your trip so that you can make full use of your time.
A.take;to B.make;for C.do;for D.write;to
3.What makes _______ possible to fly to the moon?
A.now B.man C.it D.that
