four force on the aircraft are（ ）、（ ）、（ ）and（ ）。
A: lift
B: gravity/weight
C: trust
D: drag
A: lift
B: gravity/weight
C: trust
D: drag
举一反三
- __ is a force provided by engines to push airplane forward through the air（） A: Lift B: gravity C: thrust D: drag
- Weight is the result of: A: The force on mass due to gravity B: The action of a falling mass C: How much matter the object contains D: The rate of mass per unit area
- Which forces belong to external forces(). A: spring force B: damper force C: actuator force D: gravity force
- 在顶升飞机之前，确保飞机的稳定性。 A: Make sure that the aircraft is stable before you lift it with jacks. B: Make sure that the aircraft settles before you lift it with jacks. C: Before jacking up aircraft make sure that aircraft stability is ensured. D: Before jacking up aircraft make sure that aircraft stabilization is ensured.
- Among the following forces, there are surface force （ ） A: gravity B: friction C: pressure D: surface tension E: inertial force