--- There must be a dozen pens in this house but I can never find one when I need one. --- Keep looking. _____ is sure to turn up.
I'm sorry to bother you, ____ can you direct me to the railway station?
_______you need any help, please don't hesitate to let me know.
If I had known you were coming, I ______a larger table.
I passed by Joan quickly without greeting her, ______not to see her.
The inventor was determined to go on with the experiment_______countless failures.