(define (vowel1? x)
        (member? x "auIo"))

(define (vowel2? y)
        (member? y  "eiOU"))

(define (plural wd)
     (cond 
	   ((and (empty? (keep vowel1? wd))
           (empty? (keep vowel2? wd)))
 		(word wd '?))                 
           ((vowel1? (last wd)) (word wd 'lar))
           ((vowel2? (last wd)) (word wd 'ler))
           ((vowel1? (last (bl wd))) (word wd 'lar))
           ((vowel2? (last (bl wd))) (word wd 'ler))
           ((vowel1? (last (bl (bl wd)))) (word wd 'lar))
           ((vowel2? (last (bl (bl wd)))) (word wd 'ler))
           (else (word wd '?))))