问题：
___ the red switch on the left and the flying machine will swiftly go up into the air and ____its journey.
[ ]
A. Pressing; begins
B. Press; begin
C. Pressed; begins
D. To press; to begin
___ the red switch on the left and the flying machine will swiftly go up into the air and ____its journey.
B. Press; begin
C. Pressed; begins
D. To press; to begin
[ ]
A. Pressing; begins B. Press; begin
C. Pressed; begins
D. To press; to begin
参考答案：