The wet-paint notice explicitly forbids touching the railing. The shop says keeping a paper receipt is optional because a digital copy is sufficient. Select all that apply: which sentences correctly restate those notices?

الشرح

You mustn't touch the wet railing correctly expresses the notice's direct prohibition, while don't have to would only call touching unnecessary. Customers don't have to keep the paper copy correctly removes a requirement; mustn't would incorrectly forbid an optional choice.