When the holidays were drawing near, I asked my American friends ___ was the best way to travel in the United States

There is gas _______ somewhere; can you smell it

It was not until early this morning _______ my father came back from work, which surprised us.

It giveshis life a flying start ______ he has gone abroad for further education

The roads are lined _____trees, which have been planted to hold _____the strong winds from the north