Although computers are considered the most perfect and effective de­vices in our modern time, we cannot avoid some certain problems when we are working on a computer. Letters and phone conversations are pri­vate. It is against the law to open someone's mail without (21) _________ or to listen secretly to someone's telephone conversation. And now there are laws to protect the privacy of e-mail. It is also against the law to read the messages that a person sends or receives on a computer. Although each person has a secret password for his or her e-mail, sometimes the passwords are discovered by hackers and the mail box is opened. Recently several companies (22) _________ do business on the Internet have been attacked. The attackers sent huge amounts of useless e-mails to the Web sites of these companies. The (23) _________ was to slow or stop the ability of the compa­nies to do their business. Such actions are known as "denial of service" attacks. The companies say they may have lost millions of dollars (24) _________ they were not able to provide goods and services during the attacks. Most of the companies were able to solve the problem in about three hours. The victims of the attacks included some of largest and most (25) _________ companies on the Internet, such as Yahoo, Amazon, and Corn and E-Trade.
Question 21: A. permission B. education C. invention D. construction
Question 22: A. who B. that C. whose D. when
Question 23: A. method B. control C. situation D. effect
Question 24: A. however B. therefore C. because D. although
Question 25: A. success B. successfully C. succeed D. sucessful
Giúp e ạ . E cảm ơn