—Why do you look so worried? —My computer broke down and my essay ______ unfinished since.

-----Tom. You look very bored and tired.-----Yes, I ______ my father on the farm until seven o’clock this morning.

—How long has Mary ______ Johnson?—I don’t know. I even don’t know that they had ______.

All school buses in the northwestern provinces    with satellite positioning devices next year. 

I fixed my eyes upon the newcomer, wondering whether I ________ him somewhere before．