其中有50人从事研究与开发的翻译：Of which 50 people are employed in research and development 什么意思？中文翻译英文，英文翻译中文，怎么说？

青云英语翻译

Including 50 in research and development

Of which 50 people are employed in research and development

In which has 50 people to be engaged in the research and the development

There are 50 persons were engaged in research and development

Of which 50 people are employed in research and development