PART II    PROOFREADING & ERROR CORRECTION (15 MIN.)
The following passage contains ten errors. Each line contains a maximum of one error. In each case only one word is involved. You should proofread the passage and correct it in the following way:

For a wrong word, underline the wrong word and write the correct one in the blank provided at the end of the line.

For a missing word, mark the position of the missing word with a "^" sign    and write the word you believe to be missing in the blank provided at the end    of the line.

For an unnecessary word,    cross the unnecessary word with a slash "/" and put the word in the blank provided at the end of the line.
　
The telephone system is a circuit-switched network.
For much of the history of the system, when you placed                
(26)
a call, you were renting a pair of copper wires that ran
continuously from your telephone to the other party's
phone. You had excluding use of those wires during the                
(27)
call; when you hung up, they were rented to someone
else. Today the transaction is more complicated. (your call               
may well possess a fiber-optic cable or a satellite with
hundreds of other calls), but more conceptually the system        
(28)
still works the same way. When you dial the phone, you get
a private connection of one other party.
This is an alternative network architecture called                    
(29)
packet switching, in which all stations are always connected
to the network, but they receive only the messages addressed
to them. It is as if your telephone was always tuned in to        
(30)
thousands of conversations going on the wire, but you                   
(31)
heard only the occasional word intended to you. Most                    
(32)
computer networks employ packet switching, because
it is more efficient than circuit switching when traffic
is heavy. It seems reasonable the existing packet-switched       
(33)
network will grow, and new one may be created; they could           
(34)
well absorb traffic that would otherwise go to the telephone
system and thereby reduce the need for telephone numbers.        
(35)