Preferably, {HEAD ~ the first housing} has {TAIL ~ a third engagement part} to be engaged with the first mating part 
has
Preferably , { HEAD ~ the first housing } has { TAIL ~ a third engagement part } to be engaged with the first mating part
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH