Could any one tell me what are the posts and roles of each one in a company?

I am studying business language and my teacher asked me to give the following postions in a company their roles:
HR director, Research director, Marketing director, customer service manager. sales manager.
Really I will grateful if any answer this question.

Being this is your assignment, I would be doing you a disservice to do it for you. As is said, helping someone who can help themselves is not helping.

Good luck. Google each title for starters.

Although thier roles is almost similar there may be differences in the line of their duties depending on the organisation they work with.

HR Director's role in a company includes planning, organising, directing and managing subordinate personnel involves in the day to day running of the organisation. He also oversees recruitment of personnel. Just as the names connotes, he take charge of human resources of an organisation.

2. Research Director's roles in an organisation includes directing, planning, implementation and evaluation of research materials for the overall good of the organisation. He is also responsible for making research into areas of future progress of the organisation.

3. Marketing Director's roles in an organisation includes: dirercting and working with other member of staff of the best way to market the company and its products. He develop and directs the best campaigns possible to make sure the company's product get to the desired outreach. He develops medium and long terms marketing plans for the company. He develop and direct brands that appeals to the customers.

4. The roles of customer service manager are: manages the company's relationship with the public. manages customers' desks to make sure that their enquiries are attended to promptly. boost the image of the company. he ensures that his team works to ensure that there is a cordial relationship with customers.

5. Finally, sales manager organises sales meetings to ensure the products of the company gets to the wider public. he organises sales rallies and ensures customers satisfaction. he generates proposals, letters and other correpondences for customers. he brief the management on the strategies to adopt in order to achieve a targeted marketing strategy. sales manager ensures documentation of bookings, customers feedback on products and services

A great way to get this done is to go to workopolis or monster and search for the jobs to find real job postings. You'll find a variety of different interpretations of the roles - from real life, not a text book. That should give your report some excellent depth.