Paper making began in China and from there it _____ to North Africa and Europe.

Some insects_____ the colour of their surroundings (环境) to protect themselves.

The police had to ________________ the evidence in order to arrest the thief.

When he got home, he found the door _____, the window ______, the money and the necklace in the drawer _____. 

—The head teacher said we had only three days to finish the project.—Don't worry. We have already ________ two thirds of it.