True that A funnel-shape depression of limestone dissolve by rain is called a cave?

No, a funnel-shaped depression in limestone caused by dissolution from rainwater is typically called a "sinkhole," not a cave. Sinkholes form when the surface layer collapses into an underground void, while caves are larger, underground chambers formed through the continuous erosion of limestone by acidic water over time. Both are features of karst topography but refer to different geological formations.