How to solve the problem of borrowing keys from real estate agents?

If you are an expert, write down the information by borrowing K first, and then don't borrow it on your business card. Generally, an expert will open the door for you personally, but it won't affect you to bring guests, because if you give you the key directly, you will trample on the fruits of others' labor if you secretly make a copy. Secondly, others will be responsible for the house and will not give you the key easily. If they don't borrow the key, you can directly complain to the owner, or ask the owner to call the key collector of the intermediary and ask him to arrange it.