Temporary Employment Corporation $($TEC$)$ places temporary workers in companies during peak

periods. TEC's manager gives you the following description of the business:

a$.$ TEC has a file of candidates who are willing to work.

b$.$ Each CANDIDATE has several QUALIFICATIONs. Each qualification may be earned by

more than one candidate. $($For example, it is possible for more than one candidate to have

earned a BBA degree or a Microsoft Network Certification. And clearly a candidate may have

earned a BBA and a Microsoft Network Certification.$)$

c$.$ TEC also has a list of COMPANYs that request temporaries.

d$.$ Each time a COMPANY requests a temporary employee, TEC makes an entry in the

OPENING folder. This folder contains an opening number, company name, required

qualifications, starting date, anticipated ending date, and hourly pay.

e$.$ Each opening requires only one specific or main qualification.

f$.$ When a candidate matches the qualification, $($s$)$he is given the job, and an entry is made in

the PLACEMENT Record file. This file contains an opening number, candidate number, total

hours worked, and so o