来自孟令强的问题
3.Hestartedtocollectshellsabout4yearsago.(用forabout4years替换4yearsago)
3.Hestartedtocollectshellsabout4yearsago.(用forabout4years替换4yearsago)


3.Hestartedtocollectshellsabout4yearsago.(用forabout4years替换4yearsago)
3.Hestartedtocollectshellsabout4yearsago.(用forabout4years替换4yearsago)
Hehascollectedshellsforabout4years.