这20年间，世界发生了翻天覆地的变化。时而波澜壮阔，令人振奋;时而风雨如磐，惊心动魄。

A、Over the past 20 years, the world has changed greatly. It is sometimes sweeping and inspiring and it is sometimes stormy and disquieting.
B、Over the past 20 years, the world has witnessed great changes which are sweeping and inspiring at times and stormy and disquieting at others.
C、Over the last 20 years, the world has changed greatly, sometimes sweepingly and inspiringly and sometimes stormily and disquietingly.
D、Over the last 20 years, the world has witnessed great changes, at times sweepingly and inspiringly and at others stormily and disquietingly.