(a) The opposite of 'large' is 'small' - both describe size, and 'small' begins with 'S'. (b) The opposite of 'weak' is 'strong' - both describe physical or mental strength, and 'strong' begins with 'S'. (c) The opposite of 'fast' is 'slow' - both describe speed, and 'slow' begins with 'S'. (d) The opposite of 'rough' is 'smooth' - both describe texture, and 'smooth' begins with 'S'. (e) The opposite of 'dull' is 'sharp' - both describe edge quality or brightness, and 'sharp' begins with 'S'. (f) The opposite of 'curved' is 'straight' - both describe shape or line, and 'straight' begins with 'S'. (g) The opposite of 'finish' is 'start' - both describe beginning and ending of an action, and 'start' begins with 'S'. (h) The opposite of 'addition' is 'subtraction' - both are mathematical operations, and 'subtraction' begins with 'S'. (i) The opposite of 'complicated' is 'simple' - both describe complexity, and 'simple' begins with 'S'. (j) The opposite of 'mild' is 'severe' - both describe intensity, and 'severe' begins with 'S'. (k) The opposite of 'blunt' is 'sharp' - both describe the edge of an object, and 'sharp' begins with 'S'.