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單項選擇題

（）is not a physical wall but a flow virtual data to protect the computer network.

A.data wall
B.data channel
C.database
D.firewall

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單項選擇題

（）means to provide facility for customer’s need or inquiry and arrange it.

A.service
B.business
C.customer service
D.making money

單項選擇題

Saving or reducing expenditure in business is（）

A.save money
B.increase cost
C.cost planning
D.cost control