I wondered what difficulty he had _____ the plan.
--I think we are lost. I’ve no idea where we are.--I wish we __________the map with us.
The professor can answer almost any question __________we have about any history topic.
Due to the light pollution, stars are too faint _________with naked eyes in the urban area.
--Why won’t you go to Jim’s birthday party with us?--Well, I don’t like him, if you ________know.
He failed the driving test though he __________for a long time.