Help me with this questions:

12.- When lifting flames occur, it is the result of:
a)The thermostat being turned too high
b) an oversize pilot is being used.
c) the fan in the blower compartment turning too slow
d) the limit switch not cutting the burner off in time
e) the velocity of the air-gas mixture from the port exceeding the burning speed

15.- In the fan switch the differential is referred to as:
a) The difference between the on setting of the fan and the limit switch cutout
b) The difference between the off setting of the fan and the limit switch cutout
c) The difference between the on and off setting of the fan
e) The difference between the on setting and the temperature of the room.
f) The difference between the off setting and the temperature of the room.

16) A rule of thumb for a fan switch setting is:
a.- 10 grade above the room thermostat setting.
b.- 20 grade above the room thermostat setting
c.- 30 grade above the room thermostat setting
d.- 40 grade above the room thermostat setting
e.- 45 grade above the room thermostat setting

17.- With a time on-temperature offfan switch, the heater is wired:
a)in parallel with the gas valve
b) in series with the gas valve
c)in series with the pilot control
d) in series with the thermostat heat contacts
e) in parallel with thermostat heat contacts

18.-The limit switch in the bonnet of the furnace controls the
a)pilot ignition
b)pilot switch
c)thermostat
d)gas valve
e)fan switch

19.- The limit switch is wired in series with the:
a) Fan motor b)pilot switch c)thermostat d)gas avlve e)fan switch

20.- The heat anticipator is wired:
a) in series with the fan switch b)in series with the limit switch c)in series with the pilot d)in parallel with the contacts in the thermostat e) in series with the contacts in the thermostat

22.- A flue baffle:
a) slows down the flow of combustion produced b)restrict the air flow over heat exchanger c)makes the fan motor more efficient d)regulates the flow gas to the burner e) all the above