本句使用的是現(xiàn)在完成時,現(xiàn)在完成時由"have+過去分詞"構(gòu)成.
現(xiàn)在完成時的使用有兩種情況：
1.動作在說話之前已經(jīng)完成,對說話當(dāng)時已經(jīng)產(chǎn)生影響,例如：
He has gone to Japan.(他已離開,產(chǎn)生的影響是他此時不在本地.)
I have had breakfast.(我吃過早餐,產(chǎn)生的影響是此時我不餓或者很餓,要看說話當(dāng)時的情境或語境.)
2.狀態(tài)在說話之前已經(jīng)開始,持續(xù)到現(xiàn)在,或許還會持續(xù)下去.例如：
He has studied English for 5 years.("study English"的狀態(tài)持續(xù)到現(xiàn)在,也許還在繼續(xù))
Now I have finished the work.("finish the work"的狀態(tài)持續(xù)到現(xiàn)在,不再繼續(xù))
“Some students in shanghai have had e-bags for several months.”屬于第二種情況,"have e-bags"這種狀態(tài)到目前為止已經(jīng)持續(xù)了一段時間“for several months",并且可能還在繼續(xù).