he bought a house last year.did he buy a house last year?he did not buy a house last year
问题描述：
he bought a house last year.did he buy a house last year?he did not buy a house last year
1：he bought a house last year.2：did he buy a house last year?3：he did not buy a house last year.为什么第一句用bought,而第二第三句用了buy.第一句用过去式倒还好理解,我就是不能理解第二句第三句为什么用buy与did,因为did是过去式,而buy却没有用过去式,我就是这里搞不明白.
答
第一句用bought,是因为在这里要表示“他去年买了一栋房子.”,动词buy用过去式bought,是陈述句的一般过去式.
第二句是一般疑问句的过去式,“他去年买了一栋房子吗?”,助动词do的过去式did提前,真正的动词buy用原形.
第三句是否定句的过去式,“他去年没买房子.”,只对助动词do进行否定 did not ,而真正的动词buy还是用原形.