时态Years ago we didn't know this,but recent science______that people who don't sleep well soon get ill.A.showed B.will show C.has shown D.is showing

Winnie,name one important thing we have today that we didn't have ten years ago. 时态Years ago we didn't know this,but recent science______that people who don't sleep well soon get ill.A.showed B.will show C.has shown D.is showing since years ago用于什么时态 three years ago 标志什么时态 we didn't know much about each other twenty years ago.we were guided by our intuition ;you swept me years ago和over the years用什么时态 we can fly kites seven years ago. Three years ago,we love go I began to learn English three years ago.是什么时态 His grandpa died three years ago 改为现在完成时态 时态填空She ____(work)that factory two years ago. Many years ago,people didn't have any transportation. 找出下列句子中的错误,并改正.说明原因we on Tuesday climbed a moutain.people didn‘t traveled by plane 200years ago. (we lives in shanghai) three years ago.( )three years ago?对括号部分提问 since two years ago与since two years的区别,分别用在什么时态? 例：three years ago/three years before 如何判别该使用什么时态? two years ago 和the last two years 在使用时态上的区别（有木有啊） I first met Lisa three years ago when we ___at a radio station together.A.have worked B.had been working C.were working D.had worked本句when引导的是定语从句,修饰three years ago.那么three years ago是过去时态的标志,所以答案应