| 4.By saying “Now exists the possibility of terrorism by computer”, the writer means that（句子推理）
A.some employees may erase information from payroll files.
B.students who send out a virus may do disastrous damages to thousands of computers.
C.some people may spread fear in public by destroying computer systems.
D.some terrorists are trying to contact each other using electronic mails.
（5）Yet neither business nor government has done enough to toughen its defenses against attack.For one thing, such defenses are expensive; for another, they may interrupt communication ─ the main reason for using computers in the first place.
5.The main reason why business or government has not taken tough measures to stop hacking is that
A.they will cost too much money.
B.communication may be interrupted.
C.hacking has not caused much damage.
D.tough measures are illegal.