awk '{ while(++i<=NF) printf (!a[$i]++) ? $i FS : ""; i=split("",a); print "" }' file

#!/usr/bin/env python

for line in open('temp.txt', 'r'):
    seen = []
    words = line.rstrip('\n').split()

    for word in words:
        if not word in seen:
            print word,
            seen.append(word)
    print

# cat temp.txt
pink_kite red_pen ball pink_kite ball
yellow_flower white no white no
cloud nine_pen pink cloud pink nine_pen
brown_ball white
red_bear green red_bear
white no

# python temp.py
pink_kite red_pen ball
yellow_flower white no
cloud nine_pen pink
brown_ball white
red_bear green
white no

nawk '
function re_dup(arr,n)
{
	for(i=1;i<num;i++){
		for(j=i+1;j<=num;j++){
			if (arr[i]==arr[j])
				arr[j]=""
		}
	}
}
{
	num=split($0,arr," ")
	re_dup(arr,num)
	for(i=1;i<=num;i++){
		if(arr[i]!="")
			printf("%s ",arr[i])
	}
	printf "\n"
}' filename