目前废黄铜多少钱一斤:how long have you been 用法

how long have you been 用法 How long have you been collecting shells？与How long have you collected shells?的区别 How long have you been collecting shells？与How long have you collected shells?的区别 How long have you _______(have) this book? HOW long have you been studying english 怎么回答 how long have you been in love with your boss? how long have you been in love with your boss? how long have you been keeping this to yourself? How long have you been married? 你们结婚多久了？ 改错：How long have you bought this coat you are wearing?