Нужно к неправильным глаголам добавить окончание ing. be, become, begin, blow, bring, build, burn, buy, catch, choose, come, cost, do.

Be - being, become - becoming, begin - beginning, blow - blowing, bring - bringing, build - building, burn - burning, buy - buying, catch - catching, choose - choosing, come - coming, cost - costing, do - doing, sell - selling, read - reading, write - writing.