When you can quote a specific number like a fifth of the patients were able to quit, that's compelling.
2017年6月四級真題（第三套）閱讀 Section C
英語六級真題
As Apple and several security experts have argued, an order compelling Apple to write software that gives the Fbi access to the iPhone in question would establish an unsettling precedent.
2017年12月六級真題（第三套）閱讀 Section B
Personal technology is indeed more engaging than ever, and there's no doubt companies are engineering their products and services to be more compelling and attractive.
2017年12月六級真題（第一套）閱讀 Section B
柯林斯高階英漢雙解學習詞典釋義
ADJ-GRADED
令人信服的;有說服力的
A compelling argument or reason is one that convinces you that something is true or that something should be done.
If you describe something such as a film or book, or someone's appearance, as compelling, you mean you want to keep looking at it or reading it because you find it so interesting.