    Sentence  1; Herworked. out hom. to, get through the bone,  with bis cheap,” multitoal. type knife, made.  duller. from futile attempts, to scratch away at  the rock.    Sentence   2:-He. worked: out hom. to; get. through the bone.  with bis: ‘multé-tool *? -type knife , made  daller.by futile attempts.to chip away at she  rock .    