A gas system absorbs 200J of heat and simultaneously does 300J work on surroundings at a given temperature, what is △U in joules for the gas system? A: +100 B: -200 C: +200 D: -100

Which one is TRUE in the following descriptions about the ignition system of CFM56-3 engine? ( ) A: There is no need to provide cooling air around the ignition leads to decrease temperature B: The Low-energy exciter output is 1 spark per second, 1 joules per spark. C: Only need one gasket controls the depth the igniter plugs go into the combustion chamber. D: Do not apply grease to the threads on the ignition lead end of the igniter plug.