用所给词的适当形式填空

①To make a sandwich, we need two ____ (slice) of bread, some vegetables and some meat.

② It rained hard yesterday, but ____ (luck) we brought our raincoats and didn't get wet.

③Ted told us an unusual story ____ (call) Mystery steps.

④ Cindy had fun ____ (make) flashcards with her cousin.

⑤ How old was Laura when she became a ____ (skate) champion?