{HEAD ~ A mass spectrometer} 10 comprises {TAIL ~ an ion source} 12 which generates nebulized ions which enter an ion cooler 20 via an ion source block 16 
comprises
{ HEAD ~ A mass spectrometer } 10 comprises { TAIL ~ an ion source } 12 which generates nebulized ions which enter an ion cooler 20 via an ion source block 16
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH