Advertising agencies are losing their once-powerful grip on brand marketing.广告代理公司正逐渐丧失曾经对品牌营销的有力控制。The once-powerful party has splintered into hundreds of pieces.这个曾经势力强大的党派现在已经四分五裂了。The once-powerful post unions have been cut down to size.一度强势的邮政联盟已经威风不再。