You are going to read an article about domestic dogs. Some words are missing from the text. Use the words in brackets to form the words that fit in the gaps. Then write the appropriate form of these words in the text. There might be cases when you do not have to change the word in brackets.
Use only one word for each gap.

Gap-fill exercise

Fill in all the gaps, then press "Check" to check your answers. Use the "Hint" button to get a free letter if an answer is giving you trouble. Note that you will lose points if you ask for hints!
Dogs were (1) (probable) the first domestic animals. They have accompanied humans for some 10,000 years. Some (2) (science) say that all dogs, domestic and wild, share a common ancestor in the small South Asian wolf.
Domestic dogs still share many (3) (character) features with their wild relatives. Both defend their territories and mark them by urinating on trees, rocks, fence posts, and other (4) (suit) places. Many pet dogs bury bones or favourite toys for future use, just as their wild relatives sometimes bury a kill to secure the meat for (5) (late) meals. Dogs communicate in several ways. Physical (6) (appear) is one method. Body position, movement, and facial expression often send a strong message. Many of these signals are recognisable even to humans, such as the bared teeth of an (7) (anger) or threatened animal. Dogs also communicate with a mixture of sounds, (8) (include) barks, growls, and whines. Domestic dogs are not only companions; many work (9) (hard). They guard homes, perform police and rescue work and help (10) (hunt). Some special animals even guide the blind.