The sandwich layer refers to the group of people who are incapable of buying a house outside the government's protection and market. It shows that some do not meet the conditions of low-rent housing but have no money to buy affordable housing, and some are not eligible to buy affordable housing but cannot afford commercial housing. Which of the following are most likely to be sandwich layers? ["Xiao Hu's mother wants to buy a jump-level house, but his wife wants to buy another landscape room. Xiao Hu is caught in the air.", 'Professor Zhang has never bought a house. He believes that buying a house is not as good as renting a house, and renting is not as good as borrowing a house.', 'Old Liu used his life savings to buy a three-bedroom, one-living second-hand house.', 'Xiao Li, Wang, and Liu who have just been recruited by the company live in a temporary warehouse of the company.']