have是什麼時態的標誌

現在完成時可以用來表示發生在過去某一時刻的`,持續到現在的情況,常與for,since連用.

Mary has been ill for three days.

I have lived here since 1998.

現在完成時往往同表示不確定的過去時間狀語連用,如already, yet, just, before, recently,still, lately等:

He has already obtained a scholarship.

I haven't seen much of him recently (lately).

We have seen that film before.

Have they found the missing child yet