—Do you think we can get there on time?—Yes,_________ the bus does not break down.

That art center is _______ used to be a factory, ______ millions of tractors were produced.

I think I was at school,  ______I was staying with a friend during the vacation when I heard the news.

I was about to inform you of the sudden change ______an unexpected visitor came.

—Would you like to come to dinner tonight？ —I’d like to, ___ I’m too busy.