Response to: [help] create c++ class with the help of diagram

Revision 2
Funnily, that isn't even an object model, it's a class model.

Create a class for each class in the diagram, add members for the attributes and methods, create inheritance relationships reflecting those in the diagram, ask your tutor why he's given you an invalid diagram (assuming its supposed to be UML) for the aggregations: the shared lines render them meaningless.

1. Does a house have (shared?) ref's to a flat and a plot?
2. Does a flat have a ref to a plot?

I'd question the diagram first. Its not valid UML, so it's actually impossible to correctly answer the assignment unless you make assumptions.

(Welcome to software development, sometimes (or normally) you have to refine the requirements before tackling a problem).