A service invention refers to a service invention created by an employee of an enterprise, public institution, social organization, or state agency when performing the tasks of the unit or by using the material conditions of the unit. Which of the following are service inventions. ['Uncle Zhang joined the fitness club for the elderly and invented a new type of fitness equipment.', 'Li was entrusted by the company to participate in a subject research of a university and invented a new technology.', 'Liu designed a multi-functional blackboard at home to facilitate the usual class.', 'Wang invented a multifunctional umbrella in high school and obtained a patent.']