Represent Each of the Following Requirements with an ER Diagram

Represent each of the following requirements with an ER diagram:
(a) A company called Perfect Pets runs a number of clinics. A clinic has many staff and a member of staff manages at most one clinic (not all staff manage clinics). Each clinic has a unique clinic number (clinicNo) and each member of staff has a unique staff number (staffNo).
(b) When a pet owner contacts a clinic, the owner's pet is registered with the clinic. An owner can own one or more pets, but a pet can only register with one clinic. Each owner has a unique owner number (ownerNo) and each pet has a unique pet number (petNo).
(c) When the pet comes along to the clinic, it undergoes an examination by a member of the consulting staff. The examination may result in the pet being prescribed with one or more treatments. Each examination has a unique examination number (examNo) and each type of treatment has a unique treatment number (treatNo).
(d) Represent the complete set of requirements in one ER diagram.