Grapes are to a pear as cheese is to butter. This relationship shows the grouping or category to which something belongs. Grapes and pears are fruit; cheese and butter are both dairy products.
A can of paint is to a paintbrush as a spool of thread is to a sewing needle. This is a relationship of function. Both show the tool needed to perform a task.
A trapeze performer is to a clown as swings are to a sliding boar This relationship shows a classification. Trapeze performers and clowns are found at circuses; swings and sliding boards are found on playgrounds.
Leather boots are to cow as pearl necklace is to oyster. The leather to make the boots comes from a cow; the pearls to make the necklace come from oysters.
A snow-capped mountain is to a crocodile as a cactus is to a starfish. This relationship shows an opposition. The crocodile does NOT belong on the mountain; the starfish does NOT belong in the desert.