by many years 和 for many years区别

by many years 和 for many years区别 many years before和many years ago的区别 many.Years. I ___(learn) English for many years 有for many years 用什么时态? For many years they were all Americans. for many years,people _____ electric cars. His grandparents ______(die) for many years. 关于for many years的疑惑 We______(not see)him for many years. They have ( )(成为) friends for many years many years many years ago意思