can't is the most frequent word whose pronunciation varies between /ɑː/ and /æ/ depending on dialect. A list is: after, ask, last, answer, class, half, pass, past, path, rather, dance, example, fast, glass, laugh, plant, staff, advance, advantage, branch, cast, chance, contrast, demand, glance, grant, master, photograph, sample, shan't, task, aunt, basket, bath, command, disaster, draft, draught, enhance, grass, laughter, mask, vast.