My headache______.I thought it was going away,but now it was getting worse and worse.

This kind of animal has ______ in the world.

Sam _____ some knowledge of the computer just by watching others working on it.

Some of the rubbish, such as food, paper and iron, _____ away over a long period of time. 

—Have you heard the story of "The Merchant of Venice" —No. When and where does the story ______ ?