a half-century ago的用法和样例：
- Sputnik left Earth a half century ago this month. Now proponents hope to revive the romance of human space exploration.
- The Gradall excavator difference starts with the boom.A concept born over a half century ago, aimed at increasing versatility and productivity.
- These restraints, among others, eliminated most of the distressing inconsistencies of the unsophisticated forecasting world of a half century ago.
- A half century ago when the Asia Society was founded, Asia was frozen in a cold war, wracked by poverty, and seemingly destined for desolation.
- Over a half century ago,Chinese revolutionary leader Mao Zedong said that mobilising ordinary people would bring about catastrophic defeats for enemies.