For years,doctors____millions of patients' lives with the help of microscopes.A.have saved B.are saving C.will save D.Were saving为什吗选第一个呢

for two years 是什么意思? Two years for for hundreds of years for five years 中文 for score of years for six years的同义词 for three years同义词求 Wating For You Six Years A Roadmap for Five Years for about three years(提问) Tom has( )for three years for years 用于什么时态 He died for 3 years . for years with的意思 For 25years as one WAIT-FOR-ME-FIVE-YEARS- for ages=for years么? for years and years什么意思及同义词求解答