Sentence:  She caught her mother's eye and said quickly, 'I wondered why your cardigan was <WSD>laddering</WSD>.' She looked around the kitchen. 'It is awfully cramped in here. Perhaps if we moved the table against the wall it would be better.' She found herself almost believing that Val and Mother had torn their clothes on the stove. 
Meaning of the word marked with <WSD> tags:  (to knit) Of a knitted garment: to develop a (id=knit) as a result of a broken thread.