Shell Programming and Scripting

this is the i/p file i have :

$cat test2
DISPLAY
TWO
THREE
DISPLAY
MEEN
MOVE
DISPLAY

script used :

#!/bin/sh
file='sj/test2'
while read LINE
do
echo $LINE |grep -q "DISPLAY"
if [ "$?" -eq 0 ];then
 sed /$LINE/d $file
fi
done < $file;


i am wondering why this is giving following output :

TWO
THREE
MEEN
MOVE
TWO
THREE
MEEN
MOVE
TWO
THREE
MEEN
MOVE

while read LINE
do
echo $LINE |grep -q "DISPLAY"
if [ "$?" -eq 0 ];then
 sed /$LINE/d $file
fi
done < $file;

$cat testfile.txt
1. pritnf 'this is first line ' .
2. printf ' this is second line '
   'this is continuous line ' .
3. print ' this is 3rd line '
  ' it is still there '
 ' now its over ' .
4. set a = b
5. MOVE A TO B

output :
4. set a = b
5. MOVE A TO B

sed "/'/d" $file

grep -v "'" $file

single line :
print ' this is single line'.

multiple line:
print ' this is first line '
'this is second line'
'this is third line'. ( These statements can end with either "." or " ' ")

$cat ipfile
1. print ' this is single line'.
2. print ' this is first line '
'this is second line'
'this is third line'.
3. a='this is variable value'
4.move a to b.
5. set a to 1.


O/p file should be:

3. a='this is variable value'
4.move a to b.
5. set a to 1.

1. print ' this is single line'.
2. print ' this is first line '
'this is second line'
'this is third line'.
3. a='this is variable value'
c='this is another variable'
4.move a to b.
5. set a to 1.

...
do
 echo "$LINE" | sed "/DISPLAY/d"
done ...