The important thing is that this is a major breakthrough. “breakthrough” here means an important development or achievement.
出自:国家开放大学《商务英语(本科)》

完成拼图验证

按住下方滑块,将拼图拖到缺口处后松开。

拼图背景,将小拼图拖到缺口处
向右拖动滑块