How sensors and microprocessor are used to control the central heating systems 1) one which uses an oil burner as the source of heat
2) one which uses electric radiators that are switched on and off by the microprocessor.

the answer is a

you welcome

o an

the difference is right there dont you see it

do not use any of these common illegal characters/symbols:

# pound

% percent

& ampersand

{ left curly bracket

} right curly bracket

\ back slash

< left angle bracket

> right angle bracket

* asterisk

? question mark

/ forward slash

  blank spaces

$ dollar sign

! exclamation point

' single quotes

" double quotes

: colon

@ at sign