雅思 YES NO NOT GIVENReseachers have yet to determine whether tobacco smoking really poses a threat to life expectancy.原文：Reseach teams have conducted studies that show beyond all reasonable doubt that tobacco smoking,particularly cigarette s

雅思 YES NO NOT GIVENReseachers have yet to determine whether tobacco smoking really poses a threat to life expectancy.原文：Reseach teams have conducted studies that show beyond all reasonable doubt that tobacco smoking,particularly cigarette s
雅思 YES NO NOT GIVEN
Reseachers have yet to determine whether tobacco smoking really poses a threat to life expectancy.
原文：Reseach teams have conducted studies that show beyond all reasonable doubt that tobacco smoking,particularly cigarette smoking ,is associated with a shortened life expectancy.
肯定句里面那就是“已经”但后面又有个whether~纠结啊

雅思 YES NO NOT GIVENReseachers have yet to determine whether tobacco smoking really poses a threat to life expectancy.原文：Reseach teams have conducted studies that show beyond all reasonable doubt that tobacco smoking,particularly cigarette s
yet 一般接于not后,表转折,译作“尚未”.
这句话是否省略的not或否定词?研究者--尚未--断定吸烟是否会对（良好的）生活期望造成威胁.
原文中就说了,研究者--已经完成--了一项研究来超越一个理性的质疑：...题目和原文相反,选NO.