Temporary Employment Corporation (TEC) places temporary workers in companies during peak periods. TEC's manager gives you the following description of the business:

- TEC has a file of candidates who are willing to work.
- If the candidate has worked before, that candidate has a specific job history.
- Each candidate has several qualifications.
- Each qualification may be earned by more than one candidate.

- TEC also has a list of companies that request temporaries.
- Each time a company requests a temporary employee, TEC makes an entry in the openings folder.
- This folder contains an opening number, company name, required qualifications, starting date, anticipated ending date, and hourly pay.
- Each opening requires only one specific or main qualification.

- When a candidate matches the qualification, (s)he is given the job, and an entry is made in the Placement Record folder.
- This folder contains an opening number, candidate number, total hours worked, and so on.
- In addition, an entry is made in the job history for the candidate.

- TEC uses special codes to describe a candidate's qualifications for an opening.

Construct an E-R diagram (based on a Chen's model) to represent the above requirements. Make sure you include all appropriate entities, relationships, attributes, and cardinalities.