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

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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
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

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
首先高中的英语还是希望你好好学的,对你以后的发展也是很有好处的,语法呢是has been……since"所使用的两种时态都正确.例：It is/ has been 10

c，现在完成时。
（1）强调动作是从过去持续到现在，并有可能继续持续下去。 　　（2） 强调对现在的影响或结果，此用法容易和一般过去时混淆。两者的区别是：一般过去时有动作发生的时间点，即过去某一时间发生某一动作；现在完成时则没有，即不强调是哪个时间点发生的动作，而强调过去的动作对现在造成的影响和结果。 　　（3）在过去不确定的时间里发生的动作，但是结果对现在有影响。 　　但过去分词一定要选...

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c，现在完成时。
（1）强调动作是从过去持续到现在，并有可能继续持续下去。 　　（2） 强调对现在的影响或结果，此用法容易和一般过去时混淆。两者的区别是：一般过去时有动作发生的时间点，即过去某一时间发生某一动作；现在完成时则没有，即不强调是哪个时间点发生的动作，而强调过去的动作对现在造成的影响和结果。 　　（3）在过去不确定的时间里发生的动作，但是结果对现在有影响。 　　但过去分词一定要选择准确。 　　常出现时间状语：recently,lately,since...for... ,in the past few years 。 etc.

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楼上说的很对很中式化的解释呀。。。我当初学的时候老师也是这样教的 其实没有这么麻烦 外国的老师教的就比较简单了 区分过去和完成式就是 有时间出现就是过去式 没有时间就是完成式 加上recent 最近一词更加肯定是用现在完成啦~所以 has shown

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