List the full names of 10 legislators who only have a Facebook account.
full names refers to official_full_name; only have a Facebook account refers to youtube is NULL or youtube = '', instagram is NULL or instagram = '', twitter is NULL or twitter = '', facebook is not NULL and facebook = ''
SELECT T2.official_full_name FROM `social-media` AS T1 INNER JOIN current AS T2 ON T1.bioguide = T2.bioguide_id WHERE (T1.youtube IS NULL OR T1.youtube = '') AND (T1.instagram IS NULL OR T1.instagram = '') AND (T1.twitter IS NULL OR T1.twitter = '') AND T1.facebook IS NOT NULL AND T1.facebook != ''