The tone is thoughtful while the mood is mysterious.
Answer:
Alex had helped poor people
Alex is helping poor people
For making a plane that was actually able to fly.
Answer:
YOU CAN REFERENCES: It acts as an early warning system. Fuel supports vital machine components including the engine, transmission, axels, brakes and hydraulics system. ... This provides technicians with early warnings signals for machine parts, giving customers time to replace any components that are susceptible to damage or failure.2 thg 8, 2019
Explanation:
I'm not sure but hope it helps.
