Tom is ill. What’s wrong with him —Poor boy. His illness is the _________ of eating unhealthy food.

We tried to find a table for seven, but they were all ________.

I am not sure whether I will have anything else to do tomorrow _____, I will try every possible means to come to the party[ ]

No one in the department but Tom and I ______ that the director is going to resign. [ ]

The real reason for the fire _______ a burning cigarette end.