当着陆航空器在下滑面以下时，则下滑指示显示（）。

The difference between NDB and VOR is （ ） .

Because of their high fuel consumption at low levels, （ ） prefer to remain at higher altitudes when they fly.

“Crank down the gears” means （ ） .

“Make a gear up landing” means to make a landing （ ） .

When an aircraft was in emergency after taking off, it should （ ） before landing.

“Engine flamed out “means （ ） .

“Encounter” means （ ） .

The opposite meaning of “converging” is （ ） .

Which of the following is not included in the ATC clearance?

“Recycle squawk A0612” means （ ） .