Choose the correct modal verb. Fiona _______ run in a marathon. She's broken her leg.

The correct modal verb is "isn't able to". Here's why: * The sentence implies that Fiona *cannot* run a marathon because she has a broken leg. * "isn't able to" expresses a lack of ability to do something. The completed sentence is: "Fiona isn't able to run in a marathon. She's broken her leg."