三十年来，科学家们一直在对癌症的起因展开研究的翻译：30 years, scientists have been in the study on the causes of cancer 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

For three decades, scientists have been examining the causes of cancer

30 years, scientists have been in the study on the causes of cancer

For 30 years, the scientists continuously in launch the research to cancer cause

Over the past 30 years, scientists have studied the causes of cancer

30 years, scientists have been in the study on the causes of cancer