A half-century ago,for example, producing genetic copies of animals was only a dream of scientists.

VOA: special.2010.03.23

That might not have been true a half century ago.

这在半个世纪前本无法实现。

普林斯顿公开课 - 人性课程节选

Kingsley was fascinated by how the story explores mental health care from half-a-century ago when techniques now viewed as barbaric were commonplace.

VOA: standard.2010.02.27

When the search began, a half-century ago, it seemed sensible to assume that as technological civilization increased on a planet, more and more signals would be broadcast into space.

VOA: standard.2010.04.16

The Liberal Democratic Party suffered an embarrassing defeat in the Tokyo Metropolitan Election a few weeks ago, and it is expected to lose its half-century hold on Japanese politics in the August 30 general election.

VOA: standard.2009.07.27