three and half years 等于哪一个词组?

three years and half a year three and half years 等于哪一个词组? began to skate__ A for three and a half years B three and a half years ago.说明理由 for也不可以是用在一般过去时的吗? 1：Miss Gao will stay in Nanning for about ______( )A:three months and a half B:three month and a half C:three and a half month D:three months and half2：He's been a soldier for nearly ______( )A:half and two years B:two and half yearC:two years an THREE AND A HALF怎么样 three-and-a-half billion three years and three years是什么意思 She has been skating for _____.A.three and a half years B.three and half a year为什么选A?是因为第二个后面没加s吗。a half year=half a year by three and a half billion years agoBy three and a half billion years ago the highly complicated molecule DNA had emerged.这句话中的by和ago为什么可以同时用?不都是在.之前的意思吗? three and-a-half times中文是什么? about three and a half months ago the table is____ wide.B three and half footD three and one half foot. three months and half 和three and a half months 有什么区别? three and a half years什么意思如果是3年半的话,那这里就加S?就是years的S.如果是半年的话不用加S了吧?就是a half year我讲得对不 two years and a half=two and a half years吗? three years ；或one and a half months 作主语 哪种情况下 谓语用单数 , 哪种情况下 用复数? half的用法是 one and a half years 还是one and a half year?half具体的用法? 2 years and a half 与2 and a half years用法区别是什么?其中短语结构是什么?可以说成2 years and a half year吗?