He managed to reach the summit of his career, but it was at the _________ of his health.

Her question was so difficult that I could hardly make any ____ of it at all.　 

He had the right to take ________ of the house and farm after his father died.

The law that farmers don’t need to turn over agricultural tax to the state has come into _______. 

The research showed beyond        that smoking contributes to heart disease．