A cover may be placed over {TAIL ~ the upper opening} to seal the main body against {HEAD ~ contamination}, permitting storage of the material 
A cover may be placed over { TAIL ~ the upper opening } to seal the main body against { HEAD ~ contamination } , permitting storage of the material
OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH