若加给航空活塞发动机的燃油牌号低于规定的牌号，则发动机最有可能出现（）。

An above glide slope indication from a two-bar VASI is （ ） ．

A below glide slope indication from a two-bar VASI is （ ） ．

The color of anti-collision light on the aircraft is （ ）.

The most complex approach lighting systems are designed for runways with （ ） ．

Airport lighting system should be opened twenty minutes before the aircraft is expected to （ ） ．

Large “Xs” on taxiways indicate that （ ） ．

Large “Xs” painted on runways indicate that （ ） ．

The area preceding a displaced threshold cannot be used for （ ） ．

Which statement below is not true?

If a displaced threshold marking is seen on a runway, which of the following is not true?