breakthrough       
noun [ C ] uk/ˈbreɪk.θruː/ us/ˈbreɪk.θruː/
B2 重大进展;突破
an important discovery or event that helps to improve a situation or provide an answer to a problem
  Scientists are hoping for a breakthrough in the search for a cure for cancer. 科学家们希望在治愈癌症的研究上取得突破。 
 A major breakthrough in negotiations has been achieved. 谈判有了重大进展。 
 - More examples
 - This drug has been heralded as a major breakthrough in the fight against breast cancer.
 - They had minor breakthroughs but real success eluded them.
 - Biological research has often been a precursor to medical breakthroughs which benefit patients.
 - The leaders emphasized that a substantial breakthrough had been achieved, but there was more work to be done.
 - Researchers reported another important breakthrough in cancer research.