Is this a good example, without defining "suitable pet"? No. Fish are pets, they are in a bowl, and we never touch them. If someone's perception of a pet is something you cage and look at - a Tiger is a suitable pet. Is this a possible inconsistency with test writers? The world imagined by test writers may themselves come with assumptions and in some cases lack of assumptions. On another question the word "suitable" may be interrogated instead of assumed. Interesting and annoying.