Use present perfect or present perfect progressive: 1) the girls (dance) since 3 p.m. 2) they (travel) for a month already. 3) sue (know) sally all her life. 4) alice always (want) to visit finland. 5) i (read) this book for two hours already.

The girls have been dancing since 3 p.m.
They have been travelling for a month already.
Sue has known Sally all her life.
Alice has always wanted to visit Finland
I have been reading this book for two hours already.