Original: During his adult life , Mendelssohn wrote two piano trios , seven works for string quartet , two string quintets , the octet , a sextet for piano and strings , and numerous sonatas for piano with violin , cello , and clarinet .
Simplified: Piano trios are pieces for piano , violin and cello . A piano quartet would be for piano , violin , viola and cello . String sextets are normally for two violins , two violas and two cellos .