飞机平尾升降舵转轴前加配重，主要为了（）。

Which word does not go with all the others?

Which of the following is a primary control system?

Which of the following is an assistant control system?

Which of the following is not part of empennage?

Which word does not go with all the others?

Which word does not go with all the others?

Which word does not go with all the others?

Which word does not go with all the others?

The five major component parts of an airplane are （ ） ．

The airport runway marking is colored （ ）, taxiway and aircraft parking marking is colored （ ）.