"There is/are a book and a cup on the table."
Grammar rules dictate that such sentences require a plural verb, but a lot of native speakers use singular verbs.
I made these sentence recently: "In the south of the science park were an IT centre building, woodlands, cyber security, and grassland." "There were a office with a reception area east of the woodland and a business units south of the grassland."
It seems that a native speaker would use 'was' if they wrote those sentences, and I have no idea why. Is there any English grammar rule which supports using singular verbs in such sentences.