open house
noun uk/ˌəʊ.pən ˈhaʊs/ us/ˌoʊ.pən ˈhaʊs/
[ C ] mainly US (UK usually open day)（学校、大学、工厂等接受公众参观的）接待日，开放日
a day when an organization such as a school, college, or factory allows members of the public to go in and see what happens there
[ C ]（为房屋出售设的）看房时间
a time when a house or apartment that is being sold can be looked at by the public
[ U or S ] UK随时开放;随时欢迎来客
a situation in which people welcome visitors at any time
We keep open house, so come and see us any time. 我们随时欢迎来访，什么时候来看我们都行。