Arrays of {TAIL ~ such sensors} are constructed with at least two sensors having different chemically sensitive resistors providing {HEAD ~ dissimilar such differences} in resistance 
Arrays of { TAIL ~ such sensors } are constructed with at least two sensors having different chemically sensitive resistors providing { HEAD ~ dissimilar such differences } in resistance
OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH